Oracle Prc C学习 之 Oracle动态SQL
在这里我先说遇到的一个问题
在练习的例子中加入了头文件
#include <oraca.h>
然后我怎么编译都不行，一直说找不到oraca.h
然后我把这个改成了
EXEC SQL INCLUDE oraca;
这样就顺利的编译过去了。
第一种动态SQL语句：无宿主变量的非查询语句
应用程序接收外界输入构造SQL 语句到一个字符串，然后调用
EXECUTE IMMEDIATE 命令执行这个SQL 语句。这种SQL 语句不能为SELECT 语句，不
能包含输入变量的占位符。
5.pc #include <stdio.h> #include <string.h>
EXEC SQL INCLUDE sqlca; EXEC SQL INCLUDE oraca; EXEC ORACLE OPTION(ORACA=YES); EXEC ORACLE OPTION(RELEASE_CURSOR=YES);
int main(int argc, char *argv[])
{
EXEC SQL BEGIN DECLARE SECTION;
char *username = "scott";
char *passwd = "xx";
char *dynstmt1;
char dynstmt2[10];
VARCHAR dynstmt3[80];
char dynstmt4[80];
EXEC SQL END DECLARE SECTION;
oraca.orastxtf = ORASTFERR;
EXEC SQL CONNECT :username IDENTIFIED BY :passwd;
puts("CREATE TABLE dyn1 (col1 VARCHAR2(4))");
EXEC SQL EXECUTE IMMEDIATE
"CREATE TABLE dyn1 (col1 VARCHAR2(4))";
dynstmt1 = "INSERT INTO dyn1 VALUES('TEST')";
puts(dynstmt1);
EXEC SQL EXECUTE IMMEDIATE :dynstmt1;
strncpy(dynstmt2, "COMMIT", 10);
printf("%.10s\n", dynstmt2);
EXEC SQL EXECUTE IMMEDIATE :dynstmt2;
EXEC SQL COMMIT;
/*这里我自己又完全输入一个 DROP TABLE dyn1 这个字符串，来试试*/ gets(dynstmt4); EXEC SQL EXECUTE IMMEDIATE :dynstmt4; EXEC SQL COMMIT WORK RELEASE;
return 0; }
第二种：已知输入变量个数的非查询语句
应用程序接受或组建一个SQL 语句，并通过PREPARE 和EXECUTE 语
句执行这个SQL。不能是查询语句。为输入宿主变量准备的占位符数目和输入宿主变量的
类型必须已知
6.pc #include <stdio.h> #include <string.h>
EXEC SQL BEGIN DECLARE SECTION; #define USERNAME "scott" #define PASSWD "xx"
EXEC SQL INCLUDE sqlca; EXEC SQL INCLUDE oraca; EXEC ORACLE OPTION(ORACA=YES); char *username = USERNAME; char *passwd = PASSWD; VARCHAR dynstmt[80]; int empno = 1234; int deptno1 = 20; int deptno2 = 30; EXEC SQL END DECLARE SECTION;
int main(int argc, char *argv[])
{
oraca.orastxtf = ORASTFERR;
EXEC SQL CONNECT :username IDENTIFIED BY :passwd;
strcpy(dynstmt.arr ,"INSERT INTO EMP (EMPNO, DEPTNO) VALUES (:v1, :v2)"); dynstmt.len = strlen(dynstmt.arr);
puts((char *)dynstmt.arr);
printf("v1 = %d, v2 = %d\n", empno, deptno1);
EXEC SQL PREPARE insert_sql FROM :dynstmt;
EXEC SQL EXECUTE insert_sql USING :empno, :deptno1;
EXEC SQL COMMIT;
empno ++;
EXEC SQL EXECUTE insert_sql USING :empno, :deptno2;
printf("v1 = %d, v2 = %d\n", empno, deptno2);
EXEC SQL COMMIT;
strcpy(dynstmt.arr, "DELETE FROM EMP WHERE EMPNO = :v1"); dynstmt.len = strlen(dynstmt.arr); /* 这里我还是通过从终端输入一个值来执行 */ char temp[10]; gets(temp); empno = atoi(temp);
EXEC SQL PREPARE delete_sql FROM :dynstmt; EXEC SQL EXECUTE delete_sql USING :empno; EXEC SQL COMMIT WORK RELEASE;
return 0; }
这个就是语句中带有宿主变量的，也就是说，我们一开始不知道要删除哪个，后来通过别的渠道给定要删除的这个条件。
第三种： 通过接受或构建SQL 语句，用DELCARE、PREPARE 和OPEN、FETCH、CLOSE 语句执行动态查询SQL 语句，
并访问查询结构。
适用于已知 SELECT 查询语句查询的各列、列类型、输入宿主变量数目、输入宿主变
量类型的情况
7.pc #include <stdio.h> #include <string.h>
EXEC SQL BEGIN DECLARE SECTION;
EXEC SQL INCLUDE sqlca; EXEC SQL INCLUDE oraca; EXEC ORACLE OPTION(ORACA=YES);
#define USERNAME "scott" #define PASSWD "xx"
char *username = USERNAME; char *passwd = PASSWD; VARCHAR dynstmt[80]; VARCHAR ename[10];
EXEC SQL END DECLARE SECTION;
int main(int argc, char *argv[])
{
EXEC SQL BEGIN DECLARE SECTION;
int deptno = 10;
EXEC SQL END DECLARE SECTION;
oraca.orastxtf = ORASTFERR;
EXEC SQL CONNECT :username IDENTIFIED BY :passwd;
strcpy(dynstmt.arr, "SELECT ename FROM EMP WHERE deptno = :v1"); dynstmt.len = strlen(dynstmt.arr);
EXEC SQL PREPARE select_sql FROM :dynstmt; EXEC SQL DECLARE select_cur CURSOR FOR select_sql; /*自己输入要找的条件来查找*/ char temp[10]; gets(temp); deptno = atoi(temp); EXEC SQL OPEN select_cur USING :deptno;
EXEC SQL WHENEVER NOT FOUND DO break;
while (1) {
EXEC SQL FETCH select_cur INTO :ename;
ename.arr[ename.len] = '\0';
puts((char *)ename.arr);
}
printf("\nQuery returned %d row %s.\n\n", sqlca.sqlerrd[2],
(sqlca.sqlerrd[2] == 1)?"":"s");
EXEC SQL CLOSE select_cur; EXEC SQL COMMIT WORK RELEASE;
return 0; }