１、DECODE DECODE是Oracle公司独家提供的功能，它是一个功能很强的函数。它虽然不是SQL的标准，但对于性能非常有用。openGauss中也提供了DECODE的功能。postgres=# select DECODE(3, 1,'One', 2,'Two', 3,'Three', 'Not found'); decode --- Three (1 row) ２、SYSDATE & SYSTIMESTAMP Orac...
You could use the decode function in an SQL statement as follows: select supplier_name,decode(supplier_id,1000,'IBM',10001,'Microsoft','1002','Hewlett Packard','Gateway') result from suppliers; 上面的sql语句相当于下面的IF-THEN-ELSE : IF supplier_id = 10000 THEN result := 'IBM'; ELSIF ...
You could use the decode function in an SQL statement as follows:select supplier_name,decode(supplier_id,1000,'IBM',10001,'Microsoft','1002','Hewlett Packard','Gateway') result from suppliers; 1. 2. 3. 上面的sql语句相当于下面的IF-THEN-ELSE : 复制 IFsupplier_id=10000THENresult:='IBM';...
You could use the decode function in an SQL statement as follows:select supplier_name,decode(supplier_id,1000,'IBM',10001,'Microsoft','1002','Hewlett Packard','Gateway') result from suppliers;上面的sql语句相当于下面的IF-THEN-ELSE :IF supplier_id = 10000 THENresult := 'IBM';ELSIF supplier...
You could use the decode function in an SQL statement as follows: select supplier_name,decode(supplier_id,1000,'IBM',10001,'Microsoft','1002','Hewlett Packard','Gateway') result from suppliers; 上面的sql语句相当于下面的IF-THEN-ELSE : ...
The DECODE function in Oracle is a versatile and powerful tool that allows users to perform conditional transformations on data within an SQL query. It is similar to the CASE statement, but it offers a more compact syntax, making it a popular choice for simplifying complex queries and improving...
---(重点复习:子查询、分页查询、decode) --- SQL(高级查询) --- 子查询 --- 子查询是嵌套在其它SQL语句当中的,目的是为嵌套的SQL提供数据,以便其执行。 ---查看谁的工资高于CLARK? ---1.先查CLARK的工资 SELECT sal FROM emp_RR WHERE ename='CLARK'; ...
1、DECODE DECODE是Oracle公司独家提供的功能,它是一个功能很强的函数。它虽然不是SQL的标准,但对于性能非常有用。openGauss中也提供了DECODE的功能。 postgres=# select DECODE(3, 1,'One', 2,'Two', 3,'Three', 'Not found'); decode --- Three (...
② 有的相似的语句可以用MAX+DECODE函数来处理。 ③ 在含有子查询的SQL语句中,要特别注意减少对表的查询,例如形如“UPDATE AAA T SET T.A=(...) T.B=(...) WHERE ...;”该更新的SQL语句中小括号中的大表都是一样的,且查询非常相似,这个时候可以修改为:“UPDATE AAA T SET (T.A,T.B)=(......
1、DECODE DECODE是Oracle公司独家提供的功能,它是一个功能很强的函数。它虽然不是SQL的标准,但对于性能非常有用。openGauss中也提供了DECODE的功能。 postgres=# select DECODE(3, 1,'One', 2,'Two', 3,'Three', 'Not found'); decode --- Three (1 row) 2、SYSDATE & SYSTIMESTAMP Oracle中提供了一...