sqlite3的C语言API操作数据库的实例分析

Sqlite 2020-07-01

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 ),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,(( Customer*)pData)->id,strlen( (( Customer*)pData)->id ),(( Customer*)pData)->name,strlen( (( Customer*)pData)->name ),(( Customer*)pData)->sex,strlen( (( Customer*)pData)->sex ),sqlITE_TRANSIENT ) ;
		sqlite3_bind_int( stmt2,(( Customer*)pData)->age ) ;
		sqlite3_bind_text( stmt2,(( Customer*)pData)->addr,strlen( (( Customer*)pData)->addr ),sqlITE_TRANSIENT )  ;

	}
	else if( INSERT_ORDER == nopMode )
	{
		sqlite3_bind_text( stmt2,( ( OrderInfo*)pData)->orderId,strlen( ( (OrderInfo*)pData)->orderId ),( ( OrderInfo*)pData)->buyerId,strlen( ( (OrderInfo*)pData)->buyerId ),( ( OrderInfo*)pData)->bookId,strlen( ( (OrderInfo*)pData)->bookId ),( ( 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 * 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,int nopMode,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,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,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 ),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 ;
}

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