动态SQL中DESCRIPTOR的应用

动态SQL中DESCRIPTOR的应用

王光红

动态SQL具有的灵活性是众所周知的，本人在此介绍一种应用DESCRIPTOR的动态SQL：

$short b_num;

$char *command;

$char Sql[1024];

$short flag;

$date Date;

$long Number, b_count, j;

$long prec;

$long type;

$long scale;

$double money;

sprintf(Sql, "select * from table");

$prepare qid from $Sql;

if(SQLCODE) return -1;

$declare BROWSE scroll cursor for qid;

if(SQLCODE) return -2;

$allocate descriptor 'browsdesc' with max :b_num; //在描述区分配空间，并设置最大的项目数

$get descriptor 'browsdesc' :b_count=count;//得到查询的字段个数

if(SQLCODE){

SqlErrHandle(SQLCODE, SELECT);

goto EXIT0;

}

$fetch BROWSE using sql descriptor 'browsdesc';

if(SQLCODE){

strcpy(RetPacket.data, "SELECT ERROR|");

SqlErrHandle(SQLCODE, SELECT);

goto EXIT0;

}

for(j=1;j<=b_count;j++){

$get descriptor 'browsdesc' value $j //当前字段序号

$prec=precision, /*money、decimal*/

$scale=scale, /*money、decimal*/

$type=type;

if(SQLCODE){

SqlErrHandle(SQLCODE, SELECT);

goto EXIT0;

}

switch(type){

case SQLFLOAT:

case SQLSMFLOAT:

case SQLDECIMAL:

case SQLMONEY:

if(prec)

sprintf(fmt, "%s%d.%df\0", "%",prec+1, scale);

else

strcpy(fmt, "%f");

$get descriptor 'browsdesc' value $j

$money=data;

sprintf(result, fmt, money);

if(SQLCODE==DATAISNULL) result[0]=0;

break;

default:

$get descriptor 'browsdesc' value $j

$result=data;

}//switch

if(SQLCODE==DATAISNULL) SQLCODE=0;

if(SQLCODE){

SqlErrHandle(SQLCODE, SELECT);

goto EXIT0;

}

OutPut(result);//输出结果

}//for