Sqlite Study Notes 10: Using sqlite to query and update data in C language, sqlite Study Notes

Sqlite Study Notes 10: Using sqlite to query and update data in C language, sqlite Study Notes

The third parameter in sqlite_exec () mentioned above, SQLite will call this callback function for each record processed in each SELECT statement executed in the SQL parameter.

This section adds two functions: selectFromTable and updateTable.

The instance program is as follows:

# Include <stdio. h> # include <stdlib. h> # include "sqlite/sqlite3.h" # define DB_NANE "sqlite/test. db "sqlite3 * db = NULL; char * SQL = NULL; char * zErrMsg = NULL; const char * data =" Callback function called "; /* change to global */int ret = 0; typedef enum {false, true} bool;/* typedef int (* sqlite3_callback) (void *, data provided in the 4th argument of sqlite3_exec () int, The number of columns in rowchar **, An array of st Rings representing fields in the rowchar ** An array of strings representing column names); */static int callback (void * NotUsed, int argc, char ** argv, char ** azColName) {int I = 0; for (I = 0; I <argc; I ++) {printf ("% s = % s \ n", azColName [I], argv [I]? Argv [I]: "NULL");} printf ("\ n"); return 0;} bool connectDB () {ret = sqlite3_open (DB_NANE, & db ); if (ret! = SQLITE_ OK) {fprintf (stderr, "Error open database: % s \ n", sqlite3_errmsg (db); sqlite3_free (zErrMsg); return false;} fprintf (stdout, "Successfully opened database \ n"); return true;} bool createTable () {/* 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 state Ment */ret = sqlite3_exec (db, SQL, callback, 0, & zErrMsg); if (ret! = SQLITE_ OK) {fprintf (stderr, "Error SQL: % s \ n", zErrMsg); sqlite3_free (zErrMsg); return false;} fprintf (stdout, "Successfully table created \ n"); return true;} bool insertRecords () {/* 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 */ret = sqlite3_exec (db, SQL, callback, 0, & zErrMsg); if (ret! = SQLITE_ OK) {fprintf (stderr, "SQL error: % s \ n", zErrMsg); sqlite3_free (zErrMsg); return false;} fprintf (stdout, "successfully records created \ n"); return true ;}

Bool selectFromTable ()/* Add new */{/* Create SQL statement */SQL = "SELECT * from COMPANY";/* Execute SQL statement */ret = sqlite3_exec (db, SQL, callback, (void *) data, & zErrMsg); if (ret! = SQLITE_ OK) {fprintf (stderr, "Error SQL: % s \ n", zErrMsg); sqlite3_free (zErrMsg); return false;} fprintf (stdout, "successfully operation done \ n"); return true ;}

Bool updateTable ()/* Add new */{/* Create merged SQL statement */SQL = "UPDATE COMPANY set SALARY = 25000.00 where ID = 1; "\" SELECT * from COMPANY ";/* Execute SQL statement */ret = sqlite3_exec (db, SQL, callback, (void *) data, & zErrMsg); if (ret! = SQLITE_ OK) {fprintf (stderr, "SQL error: % s \ n", zErrMsg); sqlite3_free (zErrMsg); return false;} fprintf (stdout, "Successfully operation done \ n"); return true ;}

bool closeDB(){    int ret = 0;    ret = sqlite3_close(db);    if ( ret == SQLITE_BUSY ){        return false;    }        return true;}int main(int argc, char* argv[]){    connectDB();    /*createTable();*/    /*insertRecords();*/    selectFromTable();    updateTable();    selectFromTable();    closeDB();        return 0;}

C. Connect to the sqlite database and ask how to update the data,

Small desktop database, optional access, or embedded database SQLite (do not install services) recommended (5) Access supports ODBC (Development Database interconnection, Open Data Base Connectivity), using

How does sqlite3 query all tables in the database using C language?

SELECT name FROM sqlite_master

WHERE type = 'table'
Order by name;
Use this query statement in C Language