每一种数据库提供给程序员使用的API都有其特点，根据其设计的机制不同有很大的差别，对于SQLITE3，其API的使用还是很方便很简单的。
一.sqlite3提供的一些主要的API
在前一篇博文sqlite3的c/c++接口中对其原理有了介绍，主要使用的API一般有：
（1）打开数据库
int sqlite3_open( 文件名 , sqlite3 ** ) ;
如果此文件不存在，那么就直接创建它，存在的话就直接打开。
（2）关闭数据库
int sqlite3_close( sqlite3 * ) ;
因为在前一篇中已经提到了关于所有可能用到的API，那么下面我们直接用一个实例来进行分析。
二.实例
这个实例包括：插入，删除，查找，修改。
（1）插入
//======================================================================
//
// 函数功能：向表中插入数据
//
// 函数参数：
//
// 返回值：插入失败返回0，插入成功返回1
//
//
//====================================================================
int Insert( char * szFilePath , char * szTableName , void * pData , int nOpMode )
{
sqlite3 * conn = NULL ;
int nRet ;
const char * beginSQL = "BEGIN TRANSACTION" ;
const char * commitSQL = "COMMIT" ;
char insertSqlCommand[100] ;
// 打开数据库文件
nRet = sqlite3_open( szFilePath , &conn ) ;
if( nRet != SQLITE_OK )
{
printf("加载数据库文件失败!\n") ;
sqlite3_close( conn ) ;
return 0 ;
}
// 显式开启一个事物
sqlite3_stmt * stmt = NULL ;
if( SQLITE_OK != sqlite3_prepare_v2( conn , beginSQL , strlen( beginSQL ) , &stmt , NULL ) )
{
if( stmt )
{
sqlite3_finalize( stmt ) ;
}
sqlite3_close( conn ) ;
return 0 ;
}
if( sqlite3_step( stmt ) != SQLITE_DONE )
{
sqlite3_finalize( stmt ) ;
sqlite3_close( conn ) ;
return 0 ;
}
// 构建基于绑定变量的插入数据
if( INSERT_BOOK == nOpMode )
{
strcpy( insertSqlCommand , "insert into Book values ( ? , ? , ? , ? , ? )" ) ;
}
else if( INSERT_CUSTOMER == nOpMode )
{
strcpy( insertSqlCommand , "insert into Customer values( ? , ? , ? , ? , ?)" ) ;
}
else if( INSERT_ORDER == nOpMode )
{
strcpy( insertSqlCommand , "insert into OrderInfo values( ? , ? , ? , ? )" ) ;
}
else
{
return 0 ;
}
sqlite3_stmt * stmt2 = NULL ;
if( SQLITE_OK != sqlite3_prepare_v2( conn , insertSqlCommand , strlen( insertSqlCommand ) , &stmt2 , NULL ) )
{
if( stmt2 )
{
sqlite3_finalize(stmt2 );
sqlite3_close( conn ) ;
return 0 ;
}
}
if( INSERT_BOOK == nOpMode )
{
sqlite3_bind_text( stmt2 , 1 , ((Book*)pData)->id , strlen( ((Book*)pData)->id) , SQLITE_TRANSIENT ) ;
sqlite3_bind_text( stmt2 , 2 , ((Book*)pData)->name , strlen( ((Book*)pData)->name ) , SQLITE_TRANSIENT ) ;
sqlite3_bind_text( stmt2 , 3 , ((Book*)pData)->type , strlen( ((Book*)pData)->type ) , SQLITE_TRANSIENT ) ;
sqlite3_bind_double( stmt2 , 4 , ((Book*)pData)->price ) ;
sqlite3_bind_text( stmt2 , 5 , ((Book*)pData)->content , strlen( (( Book*)pData)->content ) , SQLITE_TRANSIENT ) ;
}
else if( INSERT_CUSTOMER == nOpMode )
{
sqlite3_bind_text( stmt2 , 1 , (( Customer*)pData)->id , strlen( (( Customer*)pData)->id ) , SQLITE_TRANSIENT ) ;
sqlite3_bind_text( stmt2 , 2 , (( Customer*)pData)->name , strlen( (( Customer*)pData)->name ) , SQLITE_TRANSIENT ) ;
sqlite3_bind_text( stmt2 , 3 , (( Customer*)pData)->sex , strlen( (( Customer*)pData)->sex ) , SQLITE_TRANSIENT ) ;
sqlite3_bind_int( stmt2 , 4 , (( Customer*)pData)->age ) ;
sqlite3_bind_text( stmt2 , 5 , (( Customer*)pData)->addr , strlen( (( Customer*)pData)->addr ) , SQLITE_TRANSIENT ) ;
}
else if( INSERT_ORDER == nOpMode )
{
sqlite3_bind_text( stmt2 , 1 , ( ( OrderInfo*)pData)->orderId , strlen( ( (OrderInfo*)pData)->orderId ) , SQLITE_TRANSIENT ) ;
sqlite3_bind_text( stmt2 , 2 , ( ( OrderInfo*)pData)->buyerId , strlen( ( (OrderInfo*)pData)->buyerId ) , SQLITE_TRANSIENT ) ;
sqlite3_bind_text( stmt2 , 3 , ( ( OrderInfo*)pData)->bookId , strlen( ( (OrderInfo*)pData)->bookId ) , SQLITE_TRANSIENT ) ;
sqlite3_bind_text( stmt2 , 4 , ( ( OrderInfo*)pData)->buyType , strlen( ( (OrderInfo*)pData)->buyType ) , SQLITE_TRANSIENT ) ;
}
else
{
return 0 ;
}
if( SQLITE_DONE != sqlite3_step( stmt2 ) )
{
sqlite3_finalize( stmt2 ) ;
sqlite3_close( conn ) ;
return 0 ;
}
// 重新初始化该sqlite3_stmt绑定的对象
sqlite3_reset( stmt2 ) ;
sqlite3_finalize( stmt2 ) ;
// 提交之前的事物
sqlite3_stmt * stmt3 = NULL ;
if( SQLITE_OK != sqlite3_prepare_v2( conn , commitSQL , strlen( commitSQL ) , &stmt3 , NULL ) )
{
sqlite3_finalize( stmt3 ) ;
sqlite3_close( conn ) ;
return 0 ;
}
if( sqlite3_step( stmt3 ) != SQLITE_DONE )
{
if( stmt3 )
{
sqlite3_finalize( stmt3 ) ;
}
sqlite3_close( conn ) ;
return 0 ;
}
// 关闭数据库
sqlite3_close( conn ) ;
return 1 ;
}
（2）删除
//=================================================================
//
// 函数说明：
//
// 返回：删除成功返回1，删除失败返回0
//
//
//
//================================================================
int Delete( char * szFileName , char * szTableName , char * szKeyword , int nOpMode )
{
sqlite3 * conn = NULL ;
sqlite3_stmt * stmt = NULL ;
int nRet ;
char szSqlCommand[100] ;
nRet = sqlite3_open( szFileName , &conn ) ;
if( nRet != SQLITE_OK )
{
sqlite3_close( conn ) ;
return 0 ;
}
if( nOpMode == DELETE_BOOK_BY_BOOKID )
{
sprintf( szSqlCommand , "delete from Book where id = %s ;" , szKeyword ) ;
}
else if( nOpMode == DELETE_BOOK_BY_BOOKNAME )
{
sprintf( szSqlCommand , "delete from Book where name = %s ;" , szKeyword ) ;
}
else if( nOpMode == DELETE_BOOK_ALL_ITEMS )
{
sprintf( szSqlCommand , "delete from Book ; " ) ;
}
else if( nOpMode == DELETE_CUSTOMER_BY_ID )
{
sprintf( szSqlCommand , "delete from Customer where id = %s ;" , szKeyword ) ;
}
else if( nOpMode == DELETE_CUSTOMER_BY_NAME )
{
sprintf( szSqlCommand , "delete from Customer where name = %s ;" , szKeyword ) ;
}
else if( nOpMode == DELETE_CUSTOMER_ALL_ITEMS )
{
sprintf( szSqlCommand , "delete from Customer ;") ;
}
else if( nOpMode == DELETE_ORDER_BY_ORDERID )
{
sprintf( szSqlCommand , "delete from OrderInfo where orderid = %s ;" , szKeyword ) ;
}
else if( nOpMode == DELETE_ORDER_BY_BOOKID )
{
sprintf( szSqlCommand , "delete from OrderInfo where bookid = %s ;" , szKeyword ) ;
}
else if( nOpMode == DELETE_ORDER_BY_CUSTOMERID )
{
sprintf( szSqlCommand , "delete from OrderInfo where customerid = %s ;" , szKeyword ) ;
}
else if( nOpMode == DELETE_ORDER_ALL_ITEMS )
{
sprintf( szSqlCommand , "delete from orderInfo ;" ) ;
}
else
{
return 0 ;
}
if( SQLITE_OK != sqlite3_prepare_v2( conn , szSqlCommand , strlen( szSqlCommand ) , & stmt , NULL ) )
{
if( stmt )
{
sqlite3_finalize( stmt ) ;
}
sqlite3_close( conn ) ;
return 0 ;
}
if( sqlite3_step( stmt ) != SQLITE_DONE )
{
if( stmt )
{
sqlite3_finalize( stmt ) ;
}
sqlite3_close( conn ) ;
return 0 ;
}
// 关闭数据库
sqlite3_close( conn ) ;
return 1 ;
}
（3）查找
//=============================================================
//
// 函数说明：
//
// 返回值:返回1说明查找成功，返回0说明查找失败
//
//
//
//============================================================
int Query( char * szFilePath , char * szTableName , char * szKeyword , int nOpMode , void * pData , int & nCount )
{
sqlite3 * conn = NULL ;
int nRet = 0 ;
sqlite3_stmt * stmt1 = NULL ;
char szQueryCommand[100] ;
if( QUERY_BOOK_BY_BOOKID == nOpMode )
{
sprintf( szQueryCommand , "select * from Book where id = %s ;" , szKeyword ) ;
}
else if( QUERY_BOOK_BY_BOOKNAME == nOpMode )
{
sprintf( szQueryCommand , "select * from Book where name = %s ;" , szKeyword ) ;
}
else if( QUERY_CUSTOMER_BY_ID == nOpMode )
{
sprintf( szQueryCommand , "select * from Customer where id = %s ;" , szKeyword ) ;
}
else if( QUERY_CUSTOMER_BY_NAME == nOpMode )
{
sprintf( szQueryCommand , "select * from Customer where name = %s ;" , szKeyword ) ;
}
else if( QUERY_ORDER_ORDERID == nOpMode )
{
sprintf( szQueryCommand , "select * from OrderInfo where orderid = %s ;" , szKeyword ) ;
}
else if( QUERY_ORDER_CUSTOMERID == nOpMode )
{
sprintf( szQueryCommand , "select * from OrderInfo where customerid = %s ;" , szKeyword ) ;
}
else if( QUERY_ORDER_BOOKID == nOpMode )
{
sprintf( szQueryCommand , "select * from OrderInfo where bookid = %s ;" , szKeyword ) ;
}
else if( QUERY_BOOK_ALL_INFO == nOpMode )
{
sprintf( szQueryCommand , "select * from Book ;") ;
}
else if( QUERY_CUSTOMER_ALL_INFO == nOpMode )
{
sprintf( szQueryCommand , "select * from Customer ;") ;
}
else if( QUERY_ORDER_ALL_INFO == nOpMode )
{
sprintf( szQueryCommand , "select * from OrderInfo ;") ;
}
else if( QUERY_USERS_BY_USERNAME == nOpMode )
{
sprintf( szQueryCommand , "select * from UserStatus where name = %s ;" , szKeyword ) ;
}
else
{
return 0 ;
}
nRet = sqlite3_open( szFilePath , &conn ) ;
if( nRet != SQLITE_OK )
{
sqlite3_close( conn ) ;
return 0 ;
}
char **dbResult ;
int nRow ;
int nColumn ;
char *errorMsg = NULL ;
int index ;
nCount = 0 ;
nRet = sqlite3_get_table( conn , szQueryCommand , &dbResult , &nRow , &nColumn , &errorMsg ) ;
if( nRet == SQLITE_OK )
{
index = nColumn ;
if( nRow == 0 )
{
return 1 ;
}
if( QUERY_BOOK_ALL_INFO == nOpMode || QUERY_BOOK_BY_BOOKID == nOpMode|| QUERY_BOOK_BY_BOOKNAME == nOpMode )
{
for ( int j = 0 ; j < nRow ; j++ )
{
for( int i = 0 ; i < nColumn ; i++ )
{
if( 0 == ( i % 5 ) )
{
strcpy( ((Book*)pData)[nCount].id , dbResult[index++] ) ;
}
if( 1 == ( i % 5 ) )
{
strcpy( ((Book*)pData)[nCount].name , dbResult[index++] ) ;
}
if( 2 == ( i % 5 ) )
{
strcpy( ((Book*)pData)[nCount].type , dbResult[index++] ) ;
}
if( 3 == ( i % 5 ) )
{
double tmp = atof( dbResult[index++] ) ;
((Book*)pData)[nCount].price = tmp ;
}
if( 4 == ( i % 5 ) )
{
strcpy( ((Book*)pData)[nCount].content , dbResult[index++] ) ;
nCount++ ;
}
}
}
}
else if( QUERY_CUSTOMER_ALL_INFO == nOpMode || QUERY_CUSTOMER_BY_ID == nOpMode || QUERY_CUSTOMER_BY_NAME == nOpMode )
{
for( int j = 0 ; j < nRow ; j++ )
{
for( int i = 0 ; i < nColumn ; i++ )
{
if( 0 == ( i % 5 ) )
{
strcpy( ( ( Customer*)pData)[nCount].id , dbResult[index++] ) ;
}
if( 1 == ( i % 5 ) )
{
strcpy( ( ( Customer*)pData)[nCount].name, dbResult[index++] ) ;
}
if( 2 == ( i % 5 ) )
{
strcpy( ( ( Customer*)pData)[nCount].sex , dbResult[index++] ) ;
}
if( 3 == ( i % 5 ) )
{
int tmp = atoi( dbResult[index++] ) ;
(( Customer*)pData)[nCount].age = tmp ;
}
if( 4 == ( i % 5 ) )
{
strcpy( ( ( Customer*)pData)[nCount].addr , dbResult[index++] ) ;
nCount++ ;
}
}
}
}
else if( QUERY_ORDER_ALL_INFO == nOpMode || QUERY_ORDER_ORDERID == nOpMode || QUERY_ORDER_CUSTOMERID == nOpMode
|| QUERY_ORDER_BOOKID == nOpMode )
{
for( int j = 0 ; j < nRow ; j++ )
{
for( int i = 0 ; i < nColumn ; i++ )
{
if( 0 == ( i % 5 ) )
{
strcpy( (( OrderInfo * )pData)[nCount].orderId , dbResult[index++] ) ;
}
if( 1 == ( i % 5 ) )
{
strcpy( (( OrderInfo *)pData )[nCount].buyerId , dbResult[index++] ) ;
}
if( 2 == ( i % 5 ) )
{
strcpy( (( OrderInfo *)pData)[nCount].bookId , dbResult[index++] ) ;
}
if( 3 == ( i % 5 ) )
{
strcpy( (( OrderInfo *)pData)[nCount].buyType , dbResult[index++] ) ;
nCount++ ;
}
}
}
}
else if( QUERY_USERS_BY_USERNAME == nOpMode )
{
for( int j = 0 ; j < nRow ; j++ )
{
for( int i = 0 ; i < nColumn ; i++ )
{
if( 0 == ( i % 5 ) )
{
strcpy( (( UserStatus*)pData)[nCount].userId , dbResult[index++] ) ;
}
if( 1 == ( i % 5 ) )
{
strcpy( (( UserStatus*)pData)[nCount].userName , dbResult[index++] ) ;
}
if( 2 == ( i % 5 ) )
{
strcpy( (( UserStatus*)pData)[nCount].password , dbResult[index++] ) ;
}
if( 3 == ( i % 5 ) )
{
strcpy( (( UserStatus*)pData)[nCount].loginType , dbResult[index++] ) ;
nCount ++ ;
}
}
}
}
else
{
return 0 ;
}
}
// 释放数据
sqlite3_free_table( dbResult ) ;
// 关闭数据库
sqlite3_close( conn ) ;
return 1 ;
}
（4）修改
//=======================================================
//
// 函数说明：
//
// 返回值：修改成功返回1，修改失败返回0
//
//
//
//======================================================
int Modify( char * szFileName , char * szTableName , char * szKeyword , void * pData , int nOpMode )
{
sqlite3 * conn = NULL ;
sqlite3_stmt * stmt = NULL ;
int nRet = 0 ;
char szSqlCommnad[200] ;
nRet = sqlite3_open( szFileName , &conn ) ;
if( SQLITE_OK != nRet )
{
sqlite3_close( conn ) ;
return 0 ;
}
if( MODIFY_BOOK == nOpMode )
{
sprintf( szSqlCommnad , "update Book set id = %s , name = %s , type = %s , price = %lf , content = %s \
where id = %s ;" , ( (Book*)pData)->id , ( (Book*)pData)->name , ( (Book*)pData)->type , ( (Book*)pData)->price , \
( (Book*)pData)->content , szKeyword ) ;
}
else if( MODIFY_CUSTOMER == nOpMode )
{
sprintf( szSqlCommnad , "update Customer set id = %s , name = %s , sex = %s , age = %d , address= %s \
where id = %s ; " , (( Customer *)pData )->id , (( Customer *)pData )->name , (( Customer *)pData )->sex , \
(( Customer *)pData )->age , (( Customer *)pData )->addr , szKeyword ) ;
}
else if( MODIFY_ORDER == nOpMode )
{
sprintf( szSqlCommnad , "update OrderInfo set orderid = %s , customerid = %s , bookid = %s , buytype = %s \
where orderid = %s ;" , (( OrderInfo*)pData)->orderId , (( OrderInfo *)pData )->buyerId , (( OrderInfo *)pData )->bookId , \
(( OrderInfo *)pData )->buyType , szKeyword ) ;
}
else
{
return 0 ;
}
if( SQLITE_OK != sqlite3_prepare_v2( conn , szSqlCommnad , strlen( szSqlCommnad ) , &stmt , NULL ) )
{
if( stmt )
{
sqlite3_finalize( stmt ) ;
}
sqlite3_close( conn ) ;
return 0 ;
}
if( SQLITE_DONE != sqlite3_step( stmt) )
{
if( stmt )
{
sqlite3_finalize( stmt ) ;
}
sqlite3_close( conn ) ;
return 0 ;
}
// 关闭数据库
sqlite3_close( conn ) ;
return 1 ;
}