在我们写SQL的时候,经常会用到许多内置方法,简化了我们许多代码,也提高了效率,这篇主要总结一些常用的方法. ISNULL VS COALESCE VS NULLIF 在SQL中,NULL值是比较特殊的,所以如何处理NULL值也是要注意的: NULL + 10 = NULL NULL OR TRUE = NULL NULL OR FALSE = NULL 首先我们看一下这三个方法的定义吧: Function  Description ISNULL ISNULL validates whether…

本函数用途:返回一个Table 在Oracle中实现,范例: --在Types中: create or replace type objTable as object ( s_usercode varchar2(), s_username varchar2() ); CREATE OR REPLACE TYPE tabTemp AS TABLE OF objtable; --在Function中: --使用Pipeline管道函数和Pipe row() create or replace fun…

想必各位在开发过程中一定使用过:统计的功能,用到了很多SQL的函数,于是就直接写在Mapper文件中了: 比如: member_num,MAX(ID) AS newestLoanID,MIN (ID) AS earlyLoanID,SUM(applied_amount) AS sumLoansAmount,status select member_num,MAX(ID) AS newestLoanID,MIN (ID) AS earlyLoanID,SUM(applied_amount) AS…

Anything can be programmable with defined syntax and common lib. )) -- Add the parameters for the stored procedure here AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; DECLARE…

原文链接:https://blog.csdn.net/lanxingbudui/article/details/81736402 前言:        在SQL server中不仅可以可以使用系统自带的函数(时间函数.聚合函数.字符串函数等等),还可以根据需要自定义函数. 一.定义:用户自定义函数的类型: 1.标量值函数(返回一个标量值) 2.表格值函数(内联表格值函数.多语句表值函数,返回一个结果集即返回多个值) 二.三种自定函数的异同点1.同点: 创建定义相同: CREATE FUNCTIO…

Use UDF sys_exec to do this. You can use this link to use sys_exec function. It says, sys_exec sys_exec takes one command string argument and executes it. Syntax sys_exec(arg1) Parameters and Return Values arg1 : A command string valid for the curren…

create database Liber; use Liber; #顯示數据庫 20150210 Geovin Du 涂聚文 SHOW DATABASES; drop table BookKindList; #书目录 create table BookKindList ( BookKindID INT NOT NULL AUTO_INCREMENT, #自动增加 BookKindName nvarchar(500) not null, BookKindParent int null, PRIM…

T-SQL: declare @int int,@prov int,@city int,@str nvarchar(500) set @str='天河麗特青春:中國廣東省廣州市天河區天河路623號天河娛樂廣場麗特青春百貨一樓,塗聚文' select @int=charindex(':',@str) select @prov=charindex('省',@str) select @city=charindex('市',@str) select substring(@str,0,@int) sele…

(Sorry for that click-bait heading. Couldn’t resist ;-) ) We’re on a mission. To teach you SQL. But mostly, we want to teach you how to appreciate SQL. You’ll love it! Getting SQL right or wrong shouldn’t be about that You’re-Doing-It-Wrong™ attitude…

MySQL开启bin-log后,调用存储过程或者函数以及触发器时,会出现错误号为1418的错误: ERROR 1418 (HY000): This function has none of DETERMINISTIC, NO SQL,or READS SQL DATA in its declaration and binary logging is enabled(you *might* want to use the less safe log_bin_trust_function_creat…