If expression is NULL, this function returns 1. Otherwise, it returns 0.SyntaxISNULL(expression)Parameter ValuesParameterDescription expression Required. The value to testTechnical DetailsWorks in: From MySQL 4.
转自:https://www.yiibai.com/mysql/isnull-function.html MySQL ISNULL函数简介 ISNULL函数接受一个参数,并测试该参数是否为NULL。如果参数为NULL,则ISNULL函数返回1,否则返回0。 下面说明了ISNULL函数的语法: ISNULL(expr) SQL 请考虑以下示例: SELECTISNULL(NULL);-- 1SELECTISNULL(1);-- 0SELECTISNULL...
SUBSTR SUBSTR (str, pos)截取从pos位置开始到最后的所有str字符串,mysql中的start是从1开始的 SUBSTR (str, pos, len) 参数说明: str为列名/字符串; pos为起始位置;mysql中的起始位置pos是从1开始的;如果为正数,就表示从正数的位置往下截取字符串(起始坐标从1开始),反之如果起始位置pos为负数,那么 表示就从...
ISNULL function Posted by:ram krishna Date: February 28, 2008 10:38PM In a program, I work with SQLServer and MySql. In a particular select, for SQLServer, I have something like this: SELECT ISNULL(field,0) FROM TABLE. If the field is not null, returns its value; otherwise, 0....
/** FIELD()函数 MySQL中的field()函数,可以用来对SQL中查询结果集进行指定顺序排序 函数使用格式如下: order by field(str,str1,str2,str3,str4……),str与str1,str2,str3,str4比较,其中str指的是字段名字, 意为:字段str按照字符串str1,str2,str3,str4的顺序返回查询到的结果集。如果表中str字段值...
ISNULLin PostgreSQL does not exist. The reason is that the function is not part of the SQL standard, and PostgreSQL is not required to provide an implementation for it. Why do MySQL and SQL Server have the ISNULL function and PostgreSQL does not?
简介:MySql常用函数(逻辑判断,字符串处理,日期函数)FIND_IN_SET、IF、ISNULL、IFNULL、NULLIF、SUBSTR、SUBSTRING_INDEX、CONCAT、LENGTH 数据库版本:MySql 5.7 FIND_IN_SET 定义: 在逗号分隔的字符串列表中查找指定字符串的位置 FIND_IN_SET(str,strlist) ...
在MySQL中,当你遇到“incorrect parameter count in the call to native function 'isnull'”的错误时,通常意味着你调用的isnull函数参数个数不正确。针对你的问题,我将从以下几个方面进行解答: 1. 确认'isnull'函数的正确参数个数 在MySQL中,isnull函数用于检查一个表达式是否为NULL。它的正确语法是: sql IS...
mysql高级函数FIND_IN_SET,ENUM和SET,LOCATE,ELT,FIELD,INTERVAL,COUNT,CAST,NULLIF,ISNULL,IFNULL,IF,CONVERT,COALESCE # FIND_IN_SET FIND_IN_SET(needle,haystack)
Hi friend, i had tested ifnull function with a tipycal example and all right, but i have a problem when the function is evaluating a value returned from a table. Let me explain that. My table have two fields: roos_chamber (depth_cm decimal(4,2), densidad_r50 decimal (10,3)...