sqlite3的sql语句用法总结与SQLite生成.db-journal文件问题

这几天遇到了一个问题就是在insert以及update数据的时候，总是生成一个.db-journal文件，重新启动程序后，该文件消失，前面添加修改的数据没有成功保存。关于如何解决这个问题，网上也没有人给出详细答案，但经过几天的分析，试验，最后成功了。不知道对所有出现的这个问题都能应付的过来，解决的方法很简单，如下：

程序中使用了

sqlite3_stmt*stmt;

然后通过rc =sqlite3_prepare(db,sql,strlen(sql),&stmt,&tail);将sql语句解析到stmt中，然后对数据库操作完成之后，没有释放stmt，当我调用sqlite3_finalize(stmt);将stmt释放之后，上面的问题不在出现了。

对此sqlite中还有一对匹配的用法。如下：

sqlite3_get_table( db,&azResult,&nrow,&ncolumn,&zErrMsg );

sqlite3_free_table( azResult );

下面是一些sql语句的用法。

sprintf(sql,"INSERT INTO "Phonebook" VALUES((select min(ID)-1 from Phonebook where ID>1 and ID-1 not in (select ID from Phonebook)),'%s','%s');",p->list[1],p->list[2]);

char sql1[100];
sprintf(sql1,"select * from Phonebook where Username like '%s%%'order by Username;",buffer);

上面是关于like匹配的用法，Username like '王%' 以及Username like '王_',%用来匹配任意字符，_用来匹配一个字符。而且还要注意的是，c语言中 %的转义方式是%%，而不是%。

上面一句话是从csdn上问的结果，插入的数据，是按照ID号从小的开始插入。也就是将中间的空缺补上。

#include <stdio.h>
#include <stdlib.h>
#include "sqlite3.h"
#define _DEBUG_

int main( void )
{
sqlite3 *db=NULL;
char *zErrMsg = 0;

int rc;

///open(create) database
rc = sqlite3_open("phonebook.db",&db);
if( rc )
{
fprintf(stderr,"Can't open database: %sn",sqlite3_errmsg(db));
sqlite3_close(db);
return 0;
}
else printf("You have opened a sqlite3 database named zieckey.db successfully!nCongratulations! Have fun ! ^-^ n");

///create table
char *sql = " CREATE TABLE Call_Record(
Status CHAR(10),
Username VARCHAR(20),
Phonenubmer VARCHAR(20),
Time timestamp,
PRIMARY KEY (Status,Username)
);" ;

//上面一句用来定义两个主键
sqlite3_exec( db,&zErrMsg );

///create table2
sql = " CREATE TABLE Phonebook(
Username VARCHAR(20) PRIMARY KEY,
Phonenubmer VARCHAR(20)
);" ;
sqlite3_exec( db,&zErrMsg );

///insert database
sql = "INSERT INTO "Call_Record" VALUES('missed','Tom','15908079860',datetime('now','localtime'));" ;
sqlite3_exec( db,&zErrMsg );

sql = "INSERT INTO "Call_Record" VALUES('answered','Jack','15908079861',&zErrMsg );

sql = "INSERT INTO "Call_Record" VALUES('dialed','Merry','15908079863','Zjf','15908079864','Qcx','15908079865','MM','15908079866','JJ','15908079867','GG','15908079868','DD','15908079869','Father','15908079870',&zErrMsg );

sql = "INSERT INTO "Call_Record" VALUES('missed','Mather','15908079871',&zErrMsg );

///insert database table two
sql = "INSERT INTO "Phonebook" VALUES('Tom','15908079860');" ;
sqlite3_exec( db,&zErrMsg );

sql = "INSERT INTO "Phonebook" VALUES('Jack','15908079861');" ;
sqlite3_exec( db,&zErrMsg );

sql = "INSERT INTO "Phonebook" VALUES('Merry','15908079863');" ;
sqlite3_exec( db,&zErrMsg );

sql = "INSERT INTO "Phonebook" VALUES('Zjf','15908079864');" ;
sqlite3_exec( db,&zErrMsg );

sql = "INSERT INTO "Phonebook" VALUES('Qcx','15908079865');" ;
sqlite3_exec( db,&zErrMsg );

sql = "INSERT INTO "Phonebook" VALUES('MM','15908079866');" ;
sqlite3_exec( db,&zErrMsg );

sql = "INSERT INTO "Phonebook" VALUES('JJ','15908079867');" ;
sqlite3_exec( db,&zErrMsg );

sql = "INSERT INTO "Phonebook" VALUES('GG','15908079868');" ;
sqlite3_exec( db,&zErrMsg );

sql = "INSERT INTO "Phonebook" VALUES('DD','15908079869');" ;
sqlite3_exec( db,&zErrMsg );

sql = "INSERT INTO "Phonebook" VALUES('Father','15908079870');" ;
sqlite3_exec( db,&zErrMsg );

sql = "INSERT INTO "Phonebook" VALUES('Mather','15908079871');" ;
sqlite3_exec( db,&zErrMsg );

int nrow = 0,ncolumn = 0;
char **azResult;

///select database
sql = "SELECT * FROM Call_Record ";

//sql = "select * from Phonebook order by Username"; //默认为升序asc

//sql = "select * from Phonebook order by Username desc"; //降序

//sql = "select * from Phonebook order by (case Username when "" then 'zzzzz' else Username end);";

//sql = "select * from Phonebook order by (case Username when null then 'zzzzz' else Username end);";

//上面一句是处理空值情况(null 与"")，sqlserver默认空值为最小，使用case可以改变它查询的值。
sqlite3_get_table( db,&zErrMsg );
int i = 0 ;
printf( "row:%d column=%d n",nrow,ncolumn );
printf( "nThe result of querying is : n" );
for( i=0 ; i<( nrow + 1 ) * ncolumn ; i++ )
printf( "azResult[%d] = %sn",i,azResult[i] );

///select database
sql = "SELECT * FROM Phonebook ";
sqlite3_get_table( db,&zErrMsg );
printf( "row:%d column=%d n",azResult[i] );
/*
///delete database
sql = "DELETE FROM Call_Record WHERE Username = 'GG' ;" ;
sqlite3_exec( db,&zErrMsg );

///update database
char sql1[100];
sprintf(sql1,"UPDATE Call_Record SET Phonenubmer = '%s' WHERE Username = '%s'","10111","MM");
sqlite3_exec( db,sql1,&zErrMsg );
*/
///select database desc (jiangxupailie)
///if no desc is default(asc)
sql = "SELECT * FROM Call_Record order by Username desc";
sqlite3_get_table( db,&zErrMsg );
printf( "nnnnrow:%d column=%d ",ncolumn );
printf( "nAfter deleting,the result of querying is : n" );
for( i=0 ; i<( nrow + 1 ) * ncolumn ; i++ )
printf( "azResult[%d] = %sn",azResult[i] );

///free azResult
sqlite3_free_table( azResult );

///close db
sqlite3_close(db);
return 0;

}

另外一种查询获取列值的方法：

int i,j,rc,ncols;
char *sql;
char *tail;
char buff[100];
sqlite3_stmt *stmt;

///about dababase select
sql = "select * from Phonebook order by (case Username when "" then 'zzzzz' else Username end);";
rc = sqlite3_prepare(db,&tail);
if (rc !=SQLITE_OK)
{
break;
}
rc = sqlite3_step(stmt); //取得数据表中一行的数据
ncols = sqlite3_column_count(stmt); //获取数据表有多少列
while(rc==SQLITE_ROW) {
for (j = 0; j < ncols; j++){
sprintf(buff,"%s",sqlite3_column_text(stmt,j)); //获取一行中每一列的数据
printf("%sn",buff);
}
rc= sqlite3_step(stmt); //获取下一行数据
}

sqlite3_finalize(stmt);

http://hi.baidu.com/arise_xue/blog/item/56ec30ef9c28fde4cf1b3e9c.html/cmtid/56ec30ef244855e1cf1b3eff

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