通过

=（等号）运算符

适用于：打勾标记 Databricks SQL 打勾标记 Databricks Runtime

如果 true 等于 expr1，则返回 expr2；否则返回 false。 此函数与 ==（双等号）运算符同义。

语法

expr1 = expr2

论点

  • expr1：任何可比较类型的表达式。
  • expr2：一个与 共享expr1的表达式。

返回

一个 BOOLEAN。

示例

> SELECT 2 = 2;
 true

> SELECT 1 = '1';
 true

> SELECT true = NULL;
 NULL

> SELECT equal_null(true, NULL);
 false

> SELECT NULL = NULL;
 NULL

> SELECT equal_null(NULL, NULL);
 true

-- By default string comparisons are trailing space sensitive
-- This can be overridden by using the COLLATE clause
> SELECT 'hello' = 'hello  ' AS default,
         'hello' = 'hello  ' COLLATE UTF8_BINARY AS utf8_binary,
         'hello' = 'hello  ' COLLATE UTF8_BINARY_RTRIM AS rtrim;
 default utf8_binary rtrim
 ------- ----------- -----
 false   false       true

 -- By default string comparisons are trailing space sensitive
-- This can be overridden by using the COLLATE clause
> SELECT 'world  ' = 'world     ' AS default,
         'world  ' = 'world     ' COLLATE UTF8_BINARY AS utf8_binary,
         'world  ' = 'world     ' COLLATE UTF8_BINARY_RTRIM AS rtrim;
 default utf8_binary rtrim
 ------- ----------- -----
 false   false       true