Oracle 字符函数—CONCAT 学习_20200204

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本文介绍了Oracle数据库中的字符函数CONCAT，它用于将两个或多个字符串拼接成一个字符串。CONCAT函数等价于使用连接操作符(||)。文中通过示例展示了如何使用CONCAT函数连接字符串，例如将ename和job字段合并。

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语法：

含义：

CONCAT返回char1与串联的char2。二者char1并char2可以是任何数据类型的CHAR，VARCHAR2，NCHAR，NVARCHAR2，CLOB，或NCLOB。返回的字符串与的字符集相同char1。其数据类型取决于参数的数据类型。

这个函数相当于连接操作符(||).

示例：

SCOTT@PROD> select concat('good ','123') "concat" from dual;

concat
--------
good 123

SCOTT@PROD>

# 使用连接符连接ename和job两个字符串

# 使用 '||' 连接操作符符

SCOTT@PROD> select ename|| ' is ' || job from emp;

ENAME||'IS'||JOB
-----------------------
SMITH is CLERK
ALLEN is SALESMAN
WARD is SALESMAN
JONES is MANAGER
MARTIN is SALESMAN
BLAKE is MANAGER
CLARK is MANAGER
SCOTT is ANALYST
KING is PRESIDENT
TURNER is SALESMAN
ADAMS is CLERK
JAMES is CLERK
FORD is ANALYST
MILLER is CLERK

14 rows selected.

SCOTT@PROD>

# 使用concat，效果相同

SCOTT@PROD> select concat(concat(ename,' is '),job) from emp;

CONCAT(CONCAT(ENAME,'IS
-----------------------
SMITH is CLERK
ALLEN is SALESMAN
WARD is SALESMAN
JONES is MANAGER
MARTIN is SALESMAN
BLAKE is MANAGER
CLARK is MANAGER
SCOTT is ANALYST
KING is PRESIDENT
TURNER is SALESMAN
ADAMS is CLERK
JAMES is CLERK
FORD is ANALYST
MILLER is CLERK

14 rows selected.

SCOTT@PROD>