前面说到的 sqlite_exec() 中的第三个参数, SQLite 将为 sql 参数内执行的每个 SELECT 语句中处理的每个记录调用这个回调函数。
本节添加了两个函数,selectFromTable和updateTable.
实例程序如下:
#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";
/* 改为全局的 */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 strings 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 = %sn", 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: %sn", sqlite3_errmsg(db));
sqlite3_free(zErrMsg);
return false;
}
fprintf(stdout, "Successfully opened databasen");
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 statement */ ret = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
if( ret != SQLITE_OK ){
fprintf(stderr, "Error SQL: %sn", zErrMsg);
sqlite3_free(zErrMsg);
return false;
}
fprintf(stdout, "Successfully table createdn");
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: %sn", zErrMsg);
sqlite3_free(zErrMsg);
return false;
}
fprintf(stdout, "successfully records createdn");
return true;
}
bool selectFromTable()/*新加*/{
/* 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: %sn", zErrMsg);
sqlite3_free(zErrMsg);
return false;
}
fprintf(stdout, "successfully operation donen");
return true;
}
bool updateTable()/* 新加 */{
/* 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: %sn", 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;
}