1.如果SQL語句已經被構造在host-variable字串變數中，則

　　（1）立即執行語句：執行時編譯並執行(構造的字串SQL內部沒有“變數”引數)

　　　　exec sql execute immediate :host-variable;

　　（2）Prepare-Execute-Using語句：Prepare語句先編譯，編譯後的SQL語句允許動態引數(即允許高階語言傳遞引數到SQL語句中)，execute語句執行，用using語句將動態引數值傳遞給編譯好的SQL語句（構造的字串SQL內部有“變數”引數）

　　　　exec sql prepare sql_temp from :host-variable;　　// 預編譯

　　　　... ...

　　　　exec sql execute sql_temp using :cond-variable;　　//cond-variable 動態引數

2.Prepare-Execute-Using舉例

 1 //Prepare-Execute-Using
 2 #include<stdio.h>
 3 #include"prompt.h"
 4 exec sql include sqlca;
 5 exec sql begin declare section;
 6     char cust_id[5];
 7     char sqltext[256];
 8
 
     char user_name[20];
 9     char user_pwd[10];
10 exec sql end declare section;
11 char cid_prompt[] = "Name customer cid to be deleted: ";
12 
13 int main()
14 {
15     strcpy(sqltext,"delete from customers where cid = :dcid");
16     ... ...
17     while(prompt(cid_prompt, 1, cust_id, 4)>=0)
18
 
     {
19         exec sql whenever not found goto no_such_cid;
20         exec sql prepare delcust from :sqltext;        //為編譯提供了基礎 
21         exec sql execute delcust using :cust_id;    //cust_id是輸入的字串變數
22         exec sql commit work;
23         
24         no_such_cid:printf("No cust %s in table\n",cust_id);
25             continue; 
26     }
27     ...
28 }