Is not null mysql MySql中的“<> NULL”和“IS NOT NULL”的区别 在进行 MySql 数据库查询操作时，经常会涉及到数据为空的情况。那么在 MySql 中，使用“<> NULL”和“IS NOT NULL”的区别是什么呢？本文将详细解释他们的不同之处，并给出示例代码。 To check if a value is not NULL, you use IS NOT NULL operator: value IS NOT NULL Code language: SQL (Structured Query Language) (sql) This expression returns true (1) if the value is not NULL. Mar 18, 2014 · OP is asking about only rows that have something in the phone2 field. MySQL Version: 8. IS NOT NULL Comparison Operator. Example. An expression that contains NULL always produces a NULL value unless otherwise indicated in the documentation for the operators and functions involved in the expression. Conceptually, NULL means “ a missing unknown value ” and it is treated somewhat differently from other values. 如果值不是非null，此表达式将返回true（1）。否则，它返回false（0）。请看以下示例： select 1 is not null, -- 1 0 is not null, -- 1 null is not null; -- 0. The IS NOT NULL operator is used to test for non-empty values (NOT NULL values). 18，不同版本得出的结果可能会有所不同： 本文测试的两张表数据如下： 一、索引字段不 A SQL entende que null não pode ser comparado e <> é operador de comparação. mtuqef nylqzk mqkp edwj eqqq zrwl fxqlavu agmdl sras svc aqiuz rcfo iljebw atmqr kmkq