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ESQL編程使用說明( 三 )

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CREATE ,INSERT a table.
==============================================================================*/EXEC SQL BEGIN DECLARE SECTION ;
CHAR sno[10],sname[10],city[10];
INT status;
EXEC SQL END DECLARE SECTION ;
EXEC SQL INCLUDE USERCA;main()
{
int i;
EXEC SQL CONNECT "cobase:cobase" ;EXEC SQL CREATE TABLE S_TEST /* Create a table named S_TEST */
(SNO CHAR (9),
SNAME CHAR (20),
STATUS INT ,CITY CHAR(10));printf(" create table success,insert?");
printf(" 0 ---- no ");
printf(" 1 ---- yes ");
printf(" choice:");
scanf("%d",&i);
while(i)
{
printf("input sno:");
scanf("%s",sno);
printf("input sname:");
scanf("%s",sname);
printf("input status:");
scanf("%d",&status);
printf("input city:");
scanf("%s",city);
EXEC SQL INSERT INTO S_TEST(SNO,SNAME,STATUS,CITY)
VALUES ((:sno,:sname,:status,:city));
printf("continue?");
printf(" 0 ----terminate ");
printf(" 1 ----continue ");
printf(" choice:");
scanf("%d",&i);}
EXEC SQL COMMIT;
EXEC SQL DISCONNECT; /*log off database*/
exit(0);
}
例題程序2 (修改和刪除表中的數(shù)據(jù))/*=============================================================================
This is a sample program which include SQL sentence about
UPDATE,DELETE a table.
==============================================================================*/EXEC SQL BEGIN DECLARE SECTION ;
CHAR sno[10],sname[10],city[10];
INT status;
EXEC SQL END DECLARE SECTION ;
EXEC SQL INCLUDE USERCA;main()
{
int i;
printf("Now exec connect ...");
EXEC SQL CONNECT "COBASE:COBASE" ;

printf(" update?");
printf(" 0 ---- no ");
printf(" 1 ---- yes ");
printf(" choice:");
scanf("%d",&i);
while(i)
{
printf("input sno:");
scanf("%s",sno);
printf("input sname:");
scanf("%s",sname);
printf("input status:");
scanf("%d",&status);
printf("input city:");
scanf("%s",city);EXEC SQL UPDATE S_TEST SET sname=:sname,city=:city ,status=:status
WHERE sno=:sno;printf(" continue?");
printf(" 0 ----no ");
printf(" 1 ----yes ");
printf(" choice:");
scanf("%d",&i);
}
printf(" delete?");
printf(" 0 ---- no ");
printf(" 1 ---- yes ");
printf(" choice:");
scanf("%d",&i);
while(i)
{
printf("input sno:");
scanf("%s",sno);EXEC SQL DELETE FROM S_TEST WHERE sno=:sno;printf(" continue?");
printf(" 0 ----no ");
printf(" 1 ----yes ");
printf(" chioce:");
scanf("%d",&i);}EXEC SQL COMMIT;
EXEC SQL DISCONNECT;
exit(0);
}第三章 查 詢
在ESQL程序中,查詢可以分為兩大類型:返回一行的查詢和返回多行的查詢.對于查詢,我們不僅對其執(zhí)行得成功與否感興趣,其結(jié)果更為有用.多行查詢要用到游標(biāo)的概念,本章就介紹查詢語句和游標(biāo)的概念和使用.
3.1 SELECT 語句SELECT語句是用于完成查詢功能的SQL語句,查詢語句因?yàn)橛蟹祷氐慕Y(jié)果,故ESQL中的SELECT語句比SQL的SELECT語句多一INTO子句,INTO子句的主變量表對應(yīng)于程序中主變量,用于存放查詢返回的結(jié)果.
SELECT語句格式如下:EXEC SQL SELECT <列名> [,<列名>[,...]] INTO <主變量表>
FROM <表名> [,<表名>[,...]] [WHERE <檢索條件>];其中:1.檢索條件中允許有主變量和嵌套子查詢語句.
2.INTO后的主變量可以是數(shù)組.
3.主變量前要用":"標(biāo)志.執(zhí)行該語句時,COBASE找出表中滿足檢索條件的行,并把結(jié)果傳送到INTO子句中所對應(yīng)的主變量中.該語句的查詢結(jié)果可以是一行或多行.WHERE后的主變量叫輸入主變量,它提供了查詢所需的信息.INTO子句中的主變量叫輸出主變量,它保存SELECT語句運(yùn)行后的結(jié)果.例題程序3 (返回一行的查詢)/*=============================================================================
This is a sample program which uses SELECT statement of Esql.
It is an example of how to do querIEs that return one row.
==============================================================================*/

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