SQLite C Tutorial - SQLite Programming in C

23/08/2020 SQLite C tutorial - SQLite programming in C
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SQLite C tutorial
last modified July 6, 2020
This is a C programming tutorial for the SQLite database. It covers the basics of SQLite
programming with the C language. You might also want to check the, SQLite tutorial,
MySQL C tutorial, or PostgreSQL C tutorial on ZetCode.
SQLite database
SQLite is an embedded relational database engine. Its developers call it a self-
contained, serverless, zero-configuration, and transactional SQL database engine. It is
currently very popular and there are hundreds of millions copies worldwide in use
today. SQLite is used in the Solaris 10, Mac OS, Android, or in the iPhone. The Qt4
library has built-in support for SQLite as well as the Python and PHP. Many popular
applications use SQLite internally such as Firefox, Google Chrome, or Amarok.
The sqlite3 tool

The sqlite3 tool is a terminal based frontend to the SQLite library. It evaluates queries
interactively and displays the results in multiple formats. It can also be used within
scripts. It has its own set of meta commands including .tables, .load, .databases,
or .dump. To get the list of all instructions, we type the .help command.
Now we are going to use the sqlite3 tool to create a new database.
$ sqlite3 test.db
SQLite version 3.8.2 2013-12-06 14:53:30
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
We provide a parameter to the sqlite3 tool; test.db is a database name. It is a file

on our disk. If it is present, it is opened. If not, it is created.
sqlite> .tables
sqlite> .exit
$ ls
test.db
zetcode.com/db/sqlitec/ 1/28
The .tables command gives a list of tables in the test.db database. There are
currently no tables. The .exit command terminates the interactive session of the
sqlite3 command line tool. The ls Unix command shows the contents of the current
working directory. We can see the test.db file. All data will be stored in this single
file.
C99
This tutorial uses C99. For GNU C compiler, we need to use the -std=c99 option. For
Windows users, the Pelles C IDE is highly recommended. (MSVC does not support
C99.)
int rc = sqlite3_open("test.db", &db);
In C99, we can mix declarations with code. In older C programs, we would need to
separate this line into two lines.
SQLite C version
In the first code example, we will get the version of the SQLite database.
version.c
#include <sqlite3.h>
#include <stdio.h>
int main(void) {
printf("%s\n", sqlite3_libversion());
return 0;
}
The sqlite3_libversion() function returns a string indicating the SQLite library.
This header file defines the interface that the SQLite library presents to the client
programs. It contains definitions, function prototypes, and comments. It is an
authoritative source for SQLite API.
$ gcc -o version version.c -lsqlite3 -std=c99
We compile the program with the GNU C compiler.
$ ./version
3.8.2
This is the output of the example.
In the second example, we again get the version of the SQLite database. This time we
will use an SQL query.
version2.c
#include <stdio.h>
int main(void) {
sqlite3 *db;
sqlite3_stmt *res;
int rc = sqlite3_open(":memory:", &db);
if (rc != SQLITE_OK) {
fprintf(stderr, "Cannot open database: %s\n", sqlite3_errmsg(db));

sqlite3_close(db);
return 1;
}
rc = sqlite3_prepare_v2(db, "SELECT SQLITE_VERSION()", -1, &res, 0);
fprintf(stderr, "Failed to fetch data: %s\n", sqlite3_errmsg(db));

sqlite3_close(db);
return 1;
}
rc = sqlite3_step(res);
if (rc == SQLITE_ROW) {
printf("%s\n", sqlite3_column_text(res, 0));
}
sqlite3_finalize(res);
sqlite3_close(db);
return 0;
}
The SQLITE_VERSION() query is used to get the version of the SQLite library.
sqlite3 *db;
The sqlite3 structure defines a database handle. Each open SQLite database is
represented by a database handle.
sqlite3_stmt *res;
The sqlite3_stmt structure represents a single SQL statement.
The sqlite3_open() function opens a new database connection. Its parameters are
the database name and the database handle. The :memory: is a special database name
using which results in opening an in-memory database. The function's return code
indicates whether the database was successfully opened. The SQLITE_OK is returned
when the connection was successfully established.

sqlite3_close(db);
return 1;
}
If the return code indicates an error, we print the message to the console, close the
database handle, and terminate the program. The sqlite3_errmsg() function returns
a description of the error. Whether or not an error occurs when it is opened, resources
associated with the database connection handle should be released by passing it to
sqlite3_close() function.
rc = sqlite3_prepare_v2(db, "SELECT SQLITE_VERSION()", -1, &res, 0);
Before an SQL statement is executed, it must be first compiled into a byte-code with
one of the sqlite3_prepare* functions. (The sqlite3_prepare() function is
deprecated.)
The sqlite3_prepare_v2() function takes five parameters. The first parameter is the
database handle obtained from the sqlite3_open() function. The second parameter
is the SQL statement to be compiled. The third parameter is the maximum length of
the SQL statement measured in bytes. Passing -1 causes the SQL string to be read up to
the first zero terminator which is the end of the string here. According to the
documentation, it is possible to gain some small performance advantage by passing the
exact number of bytes of the supplied SQL string. The fourth parameter is the
statement handle. It will point to the precompiled statement if the

sqlite3_prepare_v2() runs successfully. The last parameter is a pointer to the
unused portion of the SQL statement. Only the first statement of the SQL string is
compiled, so the parameter points to what is left uncompiled. We pass 0 since the
parameter is not important for us.
On success, sqlite3_prepare_v2() returns SQLITE_OK; otherwise an error code is

returned.
fprintf(stderr, "Failed to fetch data: %s\n", sqlite3_errmsg(db));

sqlite3_close(db);
return 1;
}
This is error handling code for the sqlite3_prepare_v2() function call.
rc = sqlite3_step(res);
The sqlite3_step() runs the SQL statement. SQLITE_ROW return code indicates that
there is another row ready. Our SQL statement returns only one row of data, therefore,
we call this function only once.
The sqlite3_finalize() function destroys the prepared statement object.
sqlite3_close(db);
The sqlite3_close() function closes the database connection.
SQLite C insert data

We create a Cars table and insert several rows to it.
insert_data.c
#include <stdio.h>
int main(void) {
sqlite3 *db;
char *err_msg = 0;

sqlite3_close(db);
return 1;
}
char *sql = "DROP TABLE IF EXISTS Cars;"

"CREATE TABLE Cars(Id INT, Name TEXT, Price INT);"
"INSERT INTO Cars VALUES(1, 'Audi', 52642);"
"INSERT INTO Cars VALUES(2, 'Mercedes', 57127);"
"INSERT INTO Cars VALUES(3, 'Skoda', 9000);"
"INSERT INTO Cars VALUES(4, 'Volvo', 29000);"
"INSERT INTO Cars VALUES(5, 'Bentley', 350000);"
"INSERT INTO Cars VALUES(6, 'Citroen', 21000);"
"INSERT INTO Cars VALUES(7, 'Hummer', 41400);"
"INSERT INTO Cars VALUES(8, 'Volkswagen', 21600);";
rc = sqlite3_exec(db, sql, 0, 0, &err_msg);
if (rc != SQLITE_OK ) {
fprintf(stderr, "SQL error: %s\n", err_msg);
sqlite3_free(err_msg);
sqlite3_close(db);
return 1;
}
sqlite3_close(db);
return 0;
}
We connect to the test.db database, create a Cars table, and insert 8 rows into the
created table.
char *err_msg = 0;
If an error occurs, this pointer will point a the created error message.
The connection to the test.db database is created.
char *sql = "DROP TABLE IF EXISTS Cars;"

"CREATE TABLE Cars(Id INT, Name TEXT, Price INT);"
"INSERT INTO Cars VALUES(1, 'Audi', 52642);"
"INSERT INTO Cars VALUES(2, 'Mercedes', 57127);"

"INSERT INTO Cars VALUES(3, 'Skoda', 9000);"
"INSERT INTO Cars VALUES(4, 'Volvo', 29000);"
"INSERT INTO Cars VALUES(5, 'Bentley', 350000);"
"INSERT INTO Cars VALUES(6, 'Citroen', 21000);"
"INSERT INTO Cars VALUES(7, 'Hummer', 41400);"
"INSERT INTO Cars VALUES(8, 'Volkswagen', 21600);";
These SQL statements create a Cars table and fill it with data. The statements must be
separated by semicolons.
The sqlite3_exec() function is a convenience wrapper around

sqlite3_prepare_v2(), sqlite3_step(), and sqlite3_finalize() that allows an
application to run multiple statements of SQL without having to use a lot of C code.
The function's third parameter is a callback function invoked for each result row
coming out of the evaluated SQL statement. The fourth parameter is the first
parameter to the callback function. If we do not need them, we can pass 0 to these
parameters.
If an error occurs then the last parameter points to the allocated error message.
The allocated message string must be freed with the sqlite3_free() function call.
sqlite> .mode column

sqlite> .headers on
We verify the written data with the sqlite3 tool. First we modify the way the data is
displayed in the console. We use the column mode and turn on the headers.
sqlite> SELECT * FROM Cars;

Id Name Price
---------- ---------- ----------
1 Audi 52642
2 Mercedes 57127
3 Skoda 9000
4 Volvo 29000
5 Bentley 350000
6 Citroen 21000
7 Hummer 41400
8 Volkswagen 21600
This is the data that we have written to the Cars table.
SQLite C last inserted row id

Sometimes, we need to determine the id of the last inserted row. For this, we have the
sqlite3_last_insert_rowid() function.
last_row_id.c
#include <stdio.h>
int main(void) {
sqlite3 *db;
char *err_msg = 0;

sqlite3_close(db);
return 1;
}
char *sql = "CREATE TABLE Friends(Id INTEGER PRIMARY KEY, Name TEXT);"
"INSERT INTO Friends(Name) VALUES ('Tom');"
"INSERT INTO Friends(Name) VALUES ('Rebecca');"
"INSERT INTO Friends(Name) VALUES ('Jim');"
"INSERT INTO Friends(Name) VALUES ('Roger');"
"INSERT INTO Friends(Name) VALUES ('Robert');";
fprintf(stderr, "Failed to create table\n");

} else {
fprintf(stdout, "Table Friends created successfully\n");

}
int last_id = sqlite3_last_insert_rowid(db);

printf("The last Id of the inserted row is %d\n", last_id);
sqlite3_close(db);
return 0;
}
A Friends table is created in memory. Its Id column is automatically incremented.
char *sql = "CREATE TABLE Friends(Id INTEGER PRIMARY KEY, Name TEXT);"
"INSERT INTO Friends(Name) VALUES ('Roger');"
"INSERT INTO Friends(Name) VALUES ('Robert');";
In SQLite, INTEGER PRIMARY KEY column is auto-incremented. There is also an

AUTOINCREMENT keyword. When applied in INTEGER PRIMARY KEY AUTOINCREMENT a
slightly different algorithm for Id creation is used.
When using auto-incremented columns, we need to explicitly state the column names
except for the auto-incremented column, which is omitted.
int last_id = sqlite3_last_insert_rowid(db);

printf("The last Id of the inserted row is %d\n", last_id);
The sqlite3_last_insert_rowid() returns the row Id of the most recent successfull

insert into the table.
$ ./last_row_id
Table Friends created successfully
The last Id of the inserted row is 5
We see the output of the program.
SQLite C retrieve data

We have inserted some data into the test.db database. In the following example, we
retrieve the data from the database.
select_all.c
#include <stdio.h>
int callback(void *, int, char **, char **);
int main(void) {
sqlite3 *db;
char *err_msg = 0;
fprintf(stderr, "Cannot open database: %s\n",

sqlite3_errmsg(db));
sqlite3_close(db);
return 1;
}
char *sql = "SELECT * FROM Cars";
rc = sqlite3_exec(db, sql, callback, 0, &err_msg);
fprintf(stderr, "Failed to select data\n");

sqlite3_close(db);
return 1;
}
sqlite3_close(db);
return 0;
}
int callback(void *NotUsed, int argc, char **argv,

char **azColName) {
NotUsed = 0;
for (int i = 0; i < argc; i++) {
printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL");

}
printf("\n");
return 0;
}
We use the SELECT * FROM Cars SQL statement to retrieve all rows from the Cars
table.
This is a function prototype for the callback function that is used in conjunction with
the sqlite3_exec() function.
We connect to the test.db database.
char *sql = "SELECT * FROM Cars";
Here we define the SQL statement to select all data from the Cars table.
The sqlite3_exec() function evalues the SQL statement. Its callback function is
invoked for each result row coming out of the evaluated SQL statement.

char **azColName) {
NotUsed = 0;

}
printf("\n");
return 0;
}
The first parameter of the callback function is data provided in the 4th argument of
sqlite3_exec(); it is often not used. The second parameter is the number of columns
in the result. The third parameter is an array of strings representing fields in the row.
The last parameter is array of strings representing column names.
In the function body, we go through all columns and print their names and content.
$ ./select_all
Id = 1
Name = Audi
Price = 52642
Id = 2
Name = Mercedes
Price = 57127
Id = 3
Name = Skoda
Price = 9000
...
This is a partial output of the example.
SQLite C parameterized queries

Now we will mention parameterized queries. Parameterized queries, also called

prepared statements, increase security and performance. When we use parameterized
queries, we use placeholders instead of directly writing the values into the statements.
parameterized.c
#include <stdio.h>
int main(void) {
sqlite3 *db;
char *err_msg = 0;
sqlite3_stmt *res;

sqlite3_close(db);
return 1;
}
char *sql = "SELECT Id, Name FROM Cars WHERE Id = ?";
rc = sqlite3_prepare_v2(db, sql, -1, &res, 0);
if (rc == SQLITE_OK) {
sqlite3_bind_int(res, 1, 3);
} else {
fprintf(stderr, "Failed to execute statement: %s\n", sqlite3_errmsg(db));

}
int step = sqlite3_step(res);
if (step == SQLITE_ROW) {
printf("%s: ", sqlite3_column_text(res, 0));

sqlite3_close(db);
return 0;
}
In the example, a question mark (?) is used as a placeholder which is later replaced
with an actual value.
char *sql = "SELECT Id, Name FROM Cars WHERE Id = ?";
The question mark is used to provide an Id to the SQL query.
The sqlite3_prepare_v2() function compiles the SQL query.
sqlite3_bind_int(res, 1, 3);
The sqlite3_bind_int() binds an integer value to the prepared statement. The

placeholder is replaced with integer value 3. The function's second parameter is the
index of the SQL parameter to be set and the third parameter is the value to bind to the
parameter.
The sqlite3_step() function evaluates the SQL statement.

If there is some row of data available, we get the values of two columns with the
sqlite3_column_text() function.
$ ./parameterized
3: Skoda
The example returns the Id and the car's name.
The second example uses parameterized statements with named placeholders.
named_placeholders.c
#include <stdio.h>
int main(void) {
sqlite3 *db;
char *err_msg = 0;
sqlite3_stmt *res;

sqlite3_close(db);
return 1;
}
char *sql = "SELECT Id, Name FROM Cars WHERE Id = @id";
if (rc == SQLITE_OK) {
int idx = sqlite3_bind_parameter_index(res, "@id");

int value = 4;
sqlite3_bind_int(res, idx, value);
} else {
fprintf(stderr, "Failed to execute statement: %s\n", sqlite3_errmsg(db));

}

sqlite3_close(db);
return 0;
}
We select the name and the price of a car using named placeholders.
char *sql = "SELECT Id, Name FROM Cars WHERE Id = @id";
Named placeholders are prefixed with the colon (:) character or the at-sign (@)
character.
int idx = sqlite3_bind_parameter_index(res, "@id");
The sqlite3_bind_parameter_index() function returns the index of an SQL

parameter given its name.
SQLite C insert image

In this section, we are going to insert an image to the SQLite database. Note that some
people argue against putting images into databases. Here we only show how to do it.
We do not dwell on the technical issues of whether to save images in databases or not.
sqlite> CREATE TABLE Images(Id INTEGER PRIMARY KEY, Data BLOB);
For this example, we create a new table called Images. For the images, we use the BLOB
data type, which stands for Binary Large Objects.
insert_image.c
#include <stdio.h>
int main(int argc, char **argv) {
FILE *fp = fopen("woman.jpg", "rb");
if (fp == NULL) {
fprintf(stderr, "Cannot open image file\n");
return 1;
}
fseek(fp, 0, SEEK_END);
if (ferror(fp)) {
fprintf(stderr, "fseek() failed\n");

int r = fclose(fp);
if (r == EOF) {
fprintf(stderr, "Cannot close file handler\n");
}
return 1;
}
int flen = ftell(fp);
if (flen == -1) {
perror("error occurred");
int r = fclose(fp);
if (r == EOF) {
}
return 1;
}
fseek(fp, 0, SEEK_SET);
if (ferror(fp)) {

int r = fclose(fp);
if (r == EOF) {
}
return 1;
}
char data[flen+1];
int size = fread(data, 1, flen, fp);
if (ferror(fp)) {
fprintf(stderr, "fread() failed\n");

int r = fclose(fp);
if (r == EOF) {
}
return 1;
}
int r = fclose(fp);
if (r == EOF) {
}
sqlite3 *db;
char *err_msg = 0;

sqlite3_close(db);
return 1;
}
sqlite3_stmt *pStmt;
char *sql = "INSERT INTO Images(Data) VALUES(?)";
rc = sqlite3_prepare(db, sql, -1, &pStmt, 0);
fprintf(stderr, "Cannot prepare statement: %s\n", sqlite3_errmsg(db));
return 1;
}
sqlite3_bind_blob(pStmt, 1, data, size, SQLITE_STATIC);
rc = sqlite3_step(pStmt);
if (rc != SQLITE_DONE) {
printf("execution failed: %s", sqlite3_errmsg(db));

}
sqlite3_finalize(pStmt);
sqlite3_close(db);
return 0;
}
In this program, we read an image from the current working directory and write it into
the Images table of the SQLite test.db database.
FILE *fp = fopen("woman.jpg", "rb");
if (fp == NULL) {
return 1;
}
We read binary data from the filesystem. We have a JPG image called woman.jpg. The
fopen() function opens the specified file for for reading. It returns a pointer to a FILE
object or NULL if the operation fails.
fseek(fp, 0, SEEK_END);
if (ferror(fp)) {

int r = fclose(fp);
if (r == EOF) {
}
return 1;
}
We move the file pointer to the end of the file using the fseek() function. We need to
determine the size of the image. If an error occurs, the error indicator is set. We check
the indicator using the fseek() function. In case of an error, the opened file handler is
closed.
int flen = ftell(fp);
if (flen == -1) {
perror("error occurred");
int r = fclose(fp);
if (r == EOF) {
}
return 1;
}
For binary streams, the ftell() function returns the number of bytes from the
beginning of the file, e.g. the size of the image file. In case of an error, the function
returns -1 and the errno is set. The perror() function interprets the value of errno as
an error message, and prints it to the standard error output stream.
char data[flen+1];
This array will store the image data.
int size = fread(data, 1, flen, fp);
The fread() function reads the data from the file pointer and stores it in the data
array. The function returns the number of elements successfully read.
int r = fclose(fp);
if (r == EOF) {
}
After the data is read, we can close the file handler.
char *sql = "INSERT INTO Images(Data) VALUES(?)";
This SQL statement is used to insert the image into the database.
rc = sqlite3_prepare(db, sql, -1, &pStmt, 0);
The SQL statement is compiled.
sqlite3_bind_blob(pStmt, 1, data, size, SQLITE_STATIC);
The sqlite3_bind_blob() function binds the binary data to the compiled statement.
The SQLITE_STATIC parameter means that the pointer to the content information is
static and does not need to be freed.
The statement is executed and the image is written to the table.
SQLite C read image

In this section, we are going to perform the reverse operation. We will read an image
from the database table.
read_image.c
#include <stdio.h>
int main(void) {
FILE *fp = fopen("woman2.jpg", "wb");
if (fp == NULL) {
return 1;
}
sqlite3 *db;
char *err_msg = 0;

sqlite3_close(db);
return 1;
}
char *sql = "SELECT Data FROM Images WHERE Id = 1";
sqlite3_stmt *pStmt;
rc = sqlite3_prepare_v2(db, sql, -1, &pStmt, 0);
fprintf(stderr, "Failed to prepare statement\n");

sqlite3_close(db);
return 1;
}
int bytes = 0;
bytes = sqlite3_column_bytes(pStmt, 0);

}
fwrite(sqlite3_column_blob(pStmt, 0), bytes, 1, fp);
if (ferror(fp)) {
fprintf(stderr, "fwrite() failed\n");
return 1;
}
int r = fclose(fp);
if (r == EOF) {
}
rc = sqlite3_finalize(pStmt);
sqlite3_close(db);
return 0;
}
We read image data from the Images table and write it to another file, which we call
woman2.jpg.
FILE *fp = fopen("woman2.jpg", "wb");
if (fp == NULL) {
return 1;
}
We open a binary file in a writing mode. The data from the database is written to the
file.
char *sql = "SELECT Data FROM Images WHERE Id = 1";
This SQL statement selects data from the Images table. We obtain the binary data from
the first row.
bytes = sqlite3_column_bytes(pStmt, 0);

}
The sqlite3_column_bytes() function returns the number of bytes in the BLOB.
fwrite(sqlite3_column_blob(pStmt, 0), bytes, 1, fp);
The binary data is written to the file with the fwrite() function. The pointer to the
selected binary data is returned by the sqlite3_column_blob() function.
if (ferror(fp)) {
fprintf(stderr, "fwrite() failed\n");
return 1;
}
The ferror() function checks if the error indicator associated with the stream is set.
SQLite C metadata
Metadata is information about the data in the database. Metadata in a SQLite contains
information about the tables and columns, in which we store data. Number of rows
affected by an SQL statement is a metadata. Number of rows and columns returned in
a result set belong to metadata as well.
Metadata in SQLite can be obtained using the PRAGMA command. SQLite objects may
have attributes, which are metadata. Finally, we can also obtain specific metatada from
querying the SQLite system sqlite_master table.
column_names.c
#include <stdio.h>
int main(void) {
sqlite3 *db;
char *err_msg = 0;

sqlite3_close(db);
return 1;
}
char *sql = "PRAGMA table_info(Cars)";

sqlite3_close(db);
return 1;
}
sqlite3_close(db);
return 0;
}

char **azColName) {
NotUsed = 0;

}
printf("\n");
return 0;
}
In this example, we issue the PRAGMA table_info(tableName) command, to get

some metadata info about our Cars table.
char *sql = "PRAGMA table_info(Cars)";
The PRAGMA table_info(tableName) command returns one row for each column in
the Cars table. Columns in the result set include the column order number, column
name, data type, whether or not the column can be NULL, and the default value for the
column.
$ ./column_names
cid = 0
name = Id
type = INT
notnull = 0
dflt_value = NULL
pk = 0
...
This is output of the example.
In the next example related to the metadata, we will list all tables in the test.db
database.
list_tables.c
#include <stdio.h>
int main(void) {
sqlite3 *db;
char *err_msg = 0;

sqlite3_close(db);
return 1;
}
char *sql = "SELECT name FROM sqlite_master WHERE type='table'";
sqlite3_close(db);
return 1;
}
sqlite3_close(db);
return 0;
}

char **azColName) {
NotUsed = 0;
printf("%s\n", argv[i] ? argv[i] : "NULL");

}
return 0;
}
The code example prints all available tables in the current database to the terminal.
char *sql = "SELECT name FROM sqlite_master WHERE type='table'";
The table names are stored inside the system sqlite_master table.
$ ./list_tables
Cars
Images
This is a sample output.
SQLite C transactions
A transaction is an atomic unit of database operations against the data in one or more
databases. The effects of all the SQL statements in a transaction can be either all
committed to the database or all rolled back.
In SQLite, any command other than the SELECT will start an implicit transaction. Also,
within a transaction a command like CREATE TABLE ..., VACUUM, PRAGMA, will commit
previous changes before executing.
Manual transactions are started with the BEGIN TRANSACTION statement and finished
with the COMMIT or ROLLBACK statements.
SQLite supports three non-standard transaction levels: DEFERRED, IMMEDIATE and

EXCLUSIVE.
Autocommit
By default, SQLite version 3 operates in autocommit mode. In autocommit mode, all

changes to the database are committed as soon as all operations associated with the
current database connection complete. Autocommit mode is disabled by a BEGIN
statement and re-enabled by a COMMIT or ROLLBACK.
get_ac_mode.c
#include <stdio.h>
int main() {
sqlite3 *db;

sqlite3_close(db);
return 1;
}
printf("Autocommit: %d\n", sqlite3_get_autocommit(db));
sqlite3_close(db);
return 0;
}
This example check whether the database is in the autocommit mode.
printf("Autocommit: %d\n", sqlite3_get_autocommit(db));
The sqlite3_get_autocommit() function returns zero if the database is not in the

autocommit mode. It returns non-zero if it is in the autocommit mode.
$ ./get_ac_mode
Autocommit: 1
The example confirms that SQLite is in the autocommit mode by default.
The next example further clarifies the autocommit mode. In the autocommit mode,
each non-SELECT statement is a small transaction that is immediately committed.
autocommit.c
#include <stdio.h>
int main(void) {
sqlite3 *db;
char *err_msg = 0;

sqlite3_close(db);
return 1;
}
char *sql = "DROP TABLE IF EXISTS Friends;"

"CREATE TABLE Friends(Id INTEGER PRIMARY KEY, Name TEXT);"
"INSERT INTO Friend(Name) VALUES ('Robert');";
sqlite3_close(db);
return 1;
}
sqlite3_close(db);
return 0;
}
We create the Friends table and try to fill it with data.


"INSERT INTO Friend(Name) VALUES ('Robert');";
The last SQL statement has an error; there is no Friend table.
$ ./autocommit
SQL error: no such table: Friend
$ sqlite3 test.db
sqlite> .tables
Cars Friends Images
sqlite> SELECT * FROM Friends;
1|Tom
2|Rebecca
3|Jim
The table is created and three rows are inserted.
Transaction
In the next example, we put some SQL statements within a transaction.
transaction.c
#include <stdio.h>
int main(void) {
sqlite3 *db;
char *err_msg = 0;

sqlite3_close(db);
return 1;
}

"BEGIN TRANSACTION;"
"INSERT INTO Friend(Name) VALUES ('Robert');"
"COMMIT;";
sqlite3_close(db);
return 1;
}
sqlite3_close(db);
return 0;
}
We continue working with the Friends table.

"BEGIN TRANSACTION;"
"INSERT INTO Friend(Name) VALUES ('Robert');"
"COMMIT;";
The first statement drops the Friends table if it exists. The other statements are
placed within a transaction. Transactions work in an all-or-nothing mode. Either
everything or nothing is committed.
sqlite> .tables
Cars Images
Since the last statement had an error, the transaction was rolled back and the Friends
table was not created.
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SQLite C Tutorial - SQLite Programming in C

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23/08/2020 SQLite C tutorial - SQLite programming in C

The sqlite3 tool

We provide a parameter to the sqlite3 tool; test.db is a database name. It is a file

int rc = sqlite3_open("test.db", &db);

The sqlite3_libversion() function returns a string indicating the SQLite library.

$ gcc -o version version.c -lsqlite3 -std=c99

We compile the program with the GNU C compiler.

This is the output of the example.

int rc = sqlite3_open(":memory:", &db);

fprintf(stderr, "Cannot open database: %s\n", sqlite3_errmsg(db));

rc = sqlite3_prepare_v2(db, "SELECT SQLITE_VERSION()", -1, &res, 0);

fprintf(stderr, "Failed to fetch data: %s\n", sqlite3_errmsg(db));

The sqlite3_stmt structure represents a single SQL statement.

int rc = sqlite3_open(":memory:", &db);

fprintf(stderr, "Cannot open database: %s\n", sqlite3_errmsg(db));

rc = sqlite3_prepare_v2(db, "SELECT SQLITE_VERSION()", -1, &res, 0);

statement handle. It will point to the precompiled statement if the

On success, sqlite3_prepare_v2() returns SQLITE_OK; otherwise an error code is

fprintf(stderr, "Failed to fetch data: %s\n", sqlite3_errmsg(db));

This is error handling code for the sqlite3_prepare_v2() function call.

The sqlite3_finalize() function destroys the prepared statement object.

The sqlite3_close() function closes the database connection.

SQLite C insert data

int rc = sqlite3_open("test.db", &db);

fprintf(stderr, "Cannot open database: %s\n", sqlite3_errmsg(db));

char *sql = "DROP TABLE IF EXISTS Cars;"

rc = sqlite3_exec(db, sql, 0, 0, &err_msg);

fprintf(stderr, "SQL error: %s\n", err_msg);

int rc = sqlite3_open("test.db", &db);

The connection to the test.db database is created.

char *sql = "DROP TABLE IF EXISTS Cars;"

"INSERT INTO Cars VALUES(2, 'Mercedes', 57127);"

rc = sqlite3_exec(db, sql, 0, 0, &err_msg);

The sqlite3_exec() function is a convenience wrapper around

sqlite> .mode column

sqlite> SELECT * FROM Cars;

This is the data that we have written to the Cars table.

SQLite C last inserted row id

int rc = sqlite3_open(":memory:", &db);

fprintf(stderr, "Cannot open database: %s\n", sqlite3_errmsg(db));

rc = sqlite3_exec(db, sql, 0, 0, &err_msg);

fprintf(stderr, "Failed to create table\n");

fprintf(stdout, "Table Friends created successfully\n");

int last_id = sqlite3_last_insert_rowid(db);

A Friends table is created in memory. Its Id column is automatically incremented.

In SQLite, INTEGER PRIMARY KEY column is auto-incremented. There is also an

int last_id = sqlite3_last_insert_rowid(db);

The sqlite3_last_insert_rowid() returns the row Id of the most recent successfull

We see the output of the program.

SQLite C retrieve data

int callback(void *, int, char **, char **);

int rc = sqlite3_open("test.db", &db);

fprintf(stderr, "Cannot open database: %s\n",

char *sql = "SELECT * FROM Cars";

rc = sqlite3_exec(db, sql, callback, 0, &err_msg);

fprintf(stderr, "Failed to select data\n");

int callback(void *NotUsed, int argc, char **argv,

for (int i = 0; i < argc; i++) {

printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL");

int callback(void *, int, char **, char **);

int callback(void *, int, char , char );

char sql = "SELECT FROM Cars";

int callback(void *, int, char , char );

char sql = "SELECT FROM Cars";