C语言实现sqlite3数据库查询的基本方法

sqlite回传函数相关说了3种基本方法：callback，gettable和预处理stmt方法
下面给出测试代码和测试用数据库，代码如下
[cpp]view plaincopy 
   
 #include<stdio.h>
 #include<stdlib.h>
 #include<string.h>
 #include"sqlite3.h"
 
 //
 //typedefint(*sqlite3_callback)(
//void*data,/*Dataprovidedinthe4thargumentofsqlite3_exec()*/
//intncols,/*Thenumberofcolumnsinrow*/
//char**values,/*Anarrayofstringsrepresentingfieldsintherow*/
//char**headers/*Anarrayofstringsrepresentingcolumnnames*/
//);
 intcallback(void*data,intncols,87); background-color:inherit; font-weight:bold">char**values,87); background-color:inherit; font-weight:bold">char**headers)
 {
inti;
 intlen=0;
intll=0;
 for(i=0;i<ncols;i++)
 {
if(strlen(headers[i])>len)
 len=strlen(headers[i]);
 }
 
 ll=len-strlen(headers[i]);
 while(ll)
 fprintf(stdout,"");
 --ll;
 }
 fprintf(stdout,"%s:%s\n",headers[i],values[i]);
"\n");
return0;
intsearch_by_callback(constchar*db_name,char*sql_cmd)
inti=0;
intj=0;
intnrow=0,ncolumn=0;
char**azResult;//二维数组存放结果
 sqlite3*db=NULL;
char*zErrMsg=0;
intrc;
if(access(db_name,0)==-1)
 fprintf(stderr,"%snotfound\n",db_name);
return-1;
 rc=sqlite3_open(db_name,&db);
if(rc!=SQLITE_OK)
"%sopenfailed:%s\n",db_name,sqlite3_errmsg(db));
 sqlite3_close(db);
return-1;
//查询数据
 rc=sqlite3_exec(db,sql_cmd,callback,NULL,&zErrMsg);
if(rc!=SQLITE_OK)
 fprintf(stderr,"%s%s:%s\n",sqlite3_errmsg(db));
if(zErrMsg)
"ErrMsg=%s\n",zErrMsg);
 sqlite3_free(zErrMsg);
if(zErrMsg)
//关闭数据库
intsearch_by_table(char*sql_cmd)
inti=0;
intj=0;
//二维数组存放结果
 sqlite3*db=NULL;
char*zErrMsg=0;
intrc;
intlen=0;
 rc=sqlite3_open(db_name,&db);
 sqlite3_close(db);
//查询数据
 rc=sqlite3_get_table(db,&azResult,&nrow,&ncolumn,&zErrMsg);
 sqlite3_free_table(azResult);
for(j=0;j<ncolumn;j++)
if(strlen(azResult[j])>len)
 len=strlen(azResult[j]);
//从第0索引到第nColumn-1索引都是字段名称
//从第nColumn索引开始，后面都是字段值
for(i=0;i<nrow;i++)
intll=(len-strlen(azResult[j]));
 printf("");
 printf("%s:%s\n",azResult[j],azResult[(i+1)*ncolumn+j]);
 printf("\n");
 #if0
 printf("%s",azResult[j]);
for(i=ncolumn;i<(nrow+1)*ncolumn;i++)
if(((i-ncolumn+1)%ncolumn)==0)
 printf("%s\n",azResult[i]);
else
 printf("%s",248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; list-style-position:outside!important"> #endif
//与sqlite3_get_table对应，释放掉azResult的内存空间
intsearch_by_stmt( sqlite3_stmt*stmt=0;
intncolumn=0;
char*column_name;
intvtype,i;
 rc=sqlite3_prepare_v2(db,-1,&stmt,0);
 ncolumn=sqlite3_column_count(stmt);
while(sqlite3_step(stmt)==SQLITE_ROW)
for(i=0;i<ncolumn;i++)
 vtype=sqlite3_column_type(stmt,i);
 column_name=sqlite3_column_name(stmt,i);
switch(vtype)
caseSQLITE_NULL:
"%s:null\n",column_name);
break;
caseSQLITE_INTEGER:
"%s:%d\n",column_name,sqlite3_column_int(stmt,i));
break;
caseSQLITE_FLOAT:
"%s:%f\n",sqlite3_column_double(stmt,i));
caseSQLITE_BLOB:/*arguablyfallthrough...*/
"%s:BLOB\n",column_name);
caseSQLITE_TEXT:
default:
"%s:ERROR[%s]\n",248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; list-style-position:outside!important"> sqlite3_finalize(stmt);
//关闭数据库
return0;
intmain(intargc,87); background-color:inherit; font-weight:bold">char*argv[])
if(argc!=4)
"usage:%s[table/callback/stmt]<db_name><sql_cmd>\r\n",argv[0]);
if((strcmp(argv[1],"table")==0))
 search_by_table(argv[2],argv[3]);
else"callback")==0))
 search_by_callback(argv[2],248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; list-style-position:outside!important"> search_by_stmt(argv[2],248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important; list-style-position:outside!important"> }
编译 gcc sqlite3_search.c sqlite3.c -o sqlite3_search -lpthread -ldl
C语言实现sqlite3数据库查询的基本方法

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