SQLite - `C/C++`

Installation

Before using SQLite in a C/C++ program, we need to ensure that the SQLite library is already installed on the machine. Refer to the SQLite installation section for the installation process.

C/C++ Interface API

The following are important C&C++/SQLite interface programs that can fulfill your needs for using SQLite databases in C/C++ programs. For more details, please refer to the SQLite official documentation.

No.	API & Description
1	sqlite3_open(const char filename, sqlite3 *ppDb) <br> This routine opens a connection to an SQLite database file and returns a database connection object for use by other SQLite routines. If the filename argument is NULL or ':memory:', sqlite3_open() will create an in-memory database that only lasts for the duration of the session. If the filename is not NULL, sqlite3_open() will attempt to open the database file with the given name. If the file does not exist, sqlite3_open() will create a new database file with that name and open it.
2	sqlite3_exec(sqlite3, const char sql, sqlite_callback, void data, char *errmsg) <br> This routine provides a quick way to execute SQL commands provided by the sql parameter, which can consist of multiple SQL commands. Here, the first parameter sqlite3 is the open database object, sqlite_callback is a callback, data is passed as its first argument, and errmsg will be returned to get any errors generated by the program. The sqlite3_exec() program parses and executes each command given by the sql parameter until the end of the string or an error is encountered.
3	sqlite3_close(sqlite3*) <br> This routine closes a database connection previously opened by sqlite3_open(). All associated statements should be completed before closing the connection. If there are unfinished queries, sqlite3_close() will return SQLITE_BUSY with an error message indicating the closure is prohibited.

Connecting to the Database

The following C code snippet shows how to connect to an existing database. If the database does not exist, it will be created, and a database object will be returned.

#include <stdio.h>
#include <sqlite3.h>

int main(int argc, char* argv[])
{
   sqlite3 *db;
   char *zErrMsg = 0;
   int rc;

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

   if( rc ){
      fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
      exit(0);
   }else{
      fprintf(stderr, "Opened database successfully\n");
   }
   sqlite3_close(db);
}

Now, let's compile and run the above program to create our database test.db in the current directory. You can change the path as needed.

$gcc test.c -l sqlite3
$./a.out
Opened database successfully

If you want to use C++ source code, you can compile it as shown below:

$g++ test.c -l sqlite3

Here, link your program with the sqlite3 library to provide the necessary functions to the C program. This will create a database file test.db in your directory, and you will get the following result:

-rwxr-xr-x. 1 root root 7383 May  8 02:06 a.out
-rw-r--r--. 1 root root  323 May  8 02:05 test.c
-rw-r--r--. 1 root root    0 May  8 02:06 test.db

Creating a Table

The following C code snippet will be used to create a table in the previously created database:

#include <stdio.h>
#include <stdlib.h>
#include <sqlite3.h> 

static int callback(void *NotUsed, int argc, char **argv, char **azColName){
   int i;

for(i=0; i&lt;argc; i++){
   printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL");
}
printf("\n");
return 0;
}

int main(int argc, char* argv[])
{
   sqlite3 *db;
   char *zErrMsg = 0;
   int  rc;
   char *sql;

   /* Open database */
   rc = sqlite3_open("test.db", &db);
   if( rc ){
      fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
      exit(0);
   }else{
      fprintf(stdout, "Opened database successfully\n");
   }

   /* Create SQL statement */
   sql = "CREATE TABLE COMPANY("  \
         "ID INT PRIMARY KEY     NOT NULL," \
         "NAME           TEXT    NOT NULL," \
         "AGE            INT     NOT NULL," \
         "ADDRESS        CHAR(50)," \
         "SALARY         REAL );";

   /* Execute SQL statement */
   rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
   if( rc != SQLITE_OK ){
   fprintf(stderr, "SQL error: %s\n", zErrMsg);
      sqlite3_free(zErrMsg);
   }else{
      fprintf(stdout, "Table created successfully\n");
   }
   sqlite3_close(db);
   return 0;
}

When the above program is compiled and executed, it will create the COMPANY table in the test.db file and the final listing of the file will be as follows:

-rwxr-xr-x. 1 root root 9567 May  8 02:31 a.out
-rw-r--r--. 1 root root 1207 May  8 02:31 test.c
-rw-r--r--. 1 root root 3072 May  8 02:31 test.db

INSERT Operation

The following C code segment shows how to create records in the COMPANY table created above:

#include <stdio.h>
#include <stdlib.h>
#include <sqlite3.h>

static int callback(void *NotUsed, int argc, char **argv, char **azColName){
   int i;
   for(i=0; i&lt;argc; i++){
      printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL");
   }
   printf("\n");
   return 0;
}

int main(int argc, char* argv[])
{
   sqlite3 *db;
   char *zErrMsg = 0;
   int rc;
   char *sql;

   /* Open database */
   rc = sqlite3_open("test.db", &db);
   if( rc ){
      fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
      exit(0);
   }else{
      fprintf(stderr, "Opened database successfully\n");
   }

   /* Create SQL statement */
   sql = "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) "  \
         "VALUES (1, 'Paul', 32, 'California', 20000.00 ); " \

INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) 
VALUES (2, 'Allen', 25, 'Texas', 15000.00 ); 
INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (3, 'Teddy', 23, 'Norway', 20000.00 );
INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (4, 'Mark', 25, 'Rich-Mond ', 65000.00 );

/* Execute SQL statement */
rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
if( rc != SQLITE_OK ){
   fprintf(stderr, "SQL error: %s\n", zErrMsg);
   sqlite3_free(zErrMsg);
}else{
   fprintf(stdout, "Records created successfully\n");
}
sqlite3_close(db);
return 0;
}

When the above program is compiled and executed, it will create the given records in the COMPANY table and display the following two lines:

Opened database successfully
Records created successfully

SELECT Operation

Before we start explaining the example to fetch records, let's have a look at some details about the callback function, which will be used in our example. This callback provides a way to obtain results from the SELECT statement. It is declared as follows:

typedef int (*sqlite3_callback)(
void*,    /* Data provided in the 4th argument of sqlite3_exec() */
int,      /* The number of columns in row */
char**,   /* An array of strings representing fields in the row */
char**    /* An array of strings representing column names */
);

If the above callback is provided as the third argument in the sqlite_exec() program, SQLite will call this callback function for each record processed in every SELECT statement executed within the SQL parameter.

The following C code segment shows how to fetch and display records from the COMPANY table created earlier:

#include <stdio.h>
#include <stdlib.h>
#include <sqlite3.h>

static int callback(void *data, int argc, char **argv, char **azColName){
   int i;
   fprintf(stderr, "%s: ", (const char*)data);
   for(i=0; i&lt;argc; i++){
      printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL");
   }
   printf("\n");
   return 0;
}

int main(int argc, char* argv[])
{
   sqlite3 *db;
   char *zErrMsg = 0;
   int rc;
   char *sql;
   const char* data = "Callback function called";

   /* Open database */
   rc = sqlite3_open("test.db", &db);
   if( rc ){
      fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
      exit(0);
   }else{
      fprintf(stderr, "Opened database successfully\n");
   }

   /* Create SQL statement */
   sql = "SELECT * from COMPANY";

/* Execute SQL statement */
rc = sqlite3_exec(db, sql, callback, (void*)data, &zErrMsg);
if (rc != SQLITE_OK) {
   fprintf(stderr, "SQL error: %s\n", zErrMsg);
   sqlite3_free(zErrMsg);
} else {
   fprintf(stdout, "Operation done successfully\n");
}
sqlite3_close(db);
return 0;
}

When the above program is compiled and executed, it produces the following result:

Opened database successfully
Callback function called: ID = 1
NAME = Paul
AGE = 32
ADDRESS = California
SALARY = 20000.0

Callback function called: ID = 2
NAME = Allen
AGE = 25
ADDRESS = Texas
SALARY = 15000.0

Callback function called: ID = 3
NAME = Teddy
AGE = 23
ADDRESS = Norway
SALARY = 20000.0

Callback function called: ID = 4
NAME = Mark
AGE = 25
ADDRESS = Rich-Mond
SALARY = 65000.0

Operation done successfully

UPDATE Operation

The following C code snippet shows how to use the UPDATE statement to update any record and then fetch and display the updated records from the COMPANY table:

#include <stdio.h>
#include <stdlib.h>
#include <sqlite3.h> 

static int callback(void *data, int argc, char **argv, char **azColName){
   int i;
   fprintf(stderr, "%s: ", (const char*)data);
   for (i = 0; i < argc; i++){
      printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL");
   }
   printf("\n");
   return 0;
}

int main(int argc, char* argv[])
{
   sqlite3 *db;
   char *zErrMsg = 0;
   int rc;
   char *sql;
   const char* data = "Callback function called";

   /* Open database */
   rc = sqlite3_open("test.db", &db);
   if (rc) {
      fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
      exit(0);
   } else {
      fprintf(stderr, "Opened database successfully\n");
   }

   /* Create merged SQL statement */
   sql = "UPDATE COMPANY set SALARY = 25000.00 where ID=1; " \
         "SELECT * from COMPANY";

   /* Execute SQL statement */
   rc = sqlite3_exec(db, sql, callback, (void*)data, &zErrMsg);
   if (rc != SQLITE_OK) {
      fprintf(stderr, "SQL error: %s\n", zErrMsg);
      sqlite3_free(zErrMsg);
   } else {
      fprintf(stdout, "Operation done successfully\n");
   }
   sqlite3_close(db);
   return 0;
}

When the above program is compiled and executed, it produces the following result:

Opened database successfully
Callback function called: ID = 1
NAME = Paul
AGE = 32
ADDRESS = California
SALARY = 25000.0

Callback function called: ID = 2
NAME = Allen
AGE = 25
ADDRESS = Texas
SALARY = 15000.0

Callback function called: ID = 3
NAME = Teddy
AGE = 23
ADDRESS = Norway
SALARY = 20000.0

Callback function called: ID = 4
NAME = Mark
AGE = 25
ADDRESS = Rich-Mond
SALARY = 65000.0

Operation done successfully

AGE = 32 ADDRESS = California SALARY = 25000.0

Callback function called: ID = 2 NAME = Allen AGE = 25 ADDRESS = Texas SALARY = 15000.0

Callback function called: ID = 3 NAME = Teddy AGE = 23 ADDRESS = Norway SALARY = 20000.0

Callback function called: ID = 4 NAME = Mark AGE = 25 ADDRESS = Rich-Mond SALARY = 65000.0

Operation done successfully

DELETE Operation

The following C code snippet shows how to use the DELETE statement to delete any record and then fetch and display the remaining records from the COMPANY table:

#include <stdio.h>
#include <stdlib.h>
#include <sqlite3.h> 

static int callback(void *data, int argc, char **argv, char **azColName){
   int i;
   fprintf(stderr, "%s: ", (const char*)data);
   for(i=0; i&lt;argc; i++){
      printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL");
   }
   printf("\n");
   return 0;
}

int main(int argc, char* argv[])
{
   sqlite3 *db;
   char *zErrMsg = 0;
   int rc;
   char *sql;
   const char* data = "Callback function called";

   /* Open database */
   rc = sqlite3_open("test.db", &db);
   if( rc ){
      fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
      exit(0);
   }else{
      fprintf(stderr, "Opened database successfully\n");
   }

   /* Create merged SQL statement */
   sql = "DELETE from COMPANY where ID=2; " \
         "SELECT * from COMPANY";

   /* Execute SQL statement */
   rc = sqlite3_exec(db, sql, callback, (void*)data, &zErrMsg);
   if( rc != SQLITE_OK ){
      fprintf(stderr, "SQL error: %s\n", zErrMsg);
      sqlite3_free(zErrMsg);
   }else{
      fprintf(stdout, "Operation done successfully\n");
   }
   sqlite3_close(db);
   return 0;
}

When the above program is compiled and executed, it produces the following result:

Opened database successfully
Callback function called: ID = 1
NAME = Paul
AGE = 32
ADDRESS = California
SALARY = 20000.0

Callback function called: ID = 3
NAME = Teddy
AGE = 23
ADDRESS = Norway
SALARY = 20000.0

Callback function called: ID = 4
NAME = Mark
AGE = 25
ADDRESS = Rich-Mond
SALARY = 65000.0

Operation done successfully

❮ Sqlite Drop Table Sqlite Order By ❯

SQLite - C/C++

Installation

C/C++ Interface API

Connecting to the Database

Creating a Table

INSERT Operation

SELECT Operation

UPDATE Operation

DELETE Operation

SQLite - `C/C++`