sql - NOT IN vs NOT EXISTS - Stack Overflow
Which of these queries is the faster? NOT EXISTS: SELECT ProductID, ProductName FROM Northwind..Products p WHERE NOT EXISTS ( SELECT 1 FROM Northwind..[Order Details] od …
Should I use != or <> for not equal in T-SQL? - Stack Overflow
Yes; Microsoft themselves recommend using <> over != specifically for ANSI compliance, e.g. in Microsoft Press training kit for 70-461 exam, "Querying Microsoft SQL Server", they say "As an …
sql - Not equal <> != operator on NULL - Stack Overflow
2011年4月14日 · 11 In SQL, anything you evaluate / compute with NULL results into UNKNOWN This is why SELECT * FROM MyTable WHERE MyColumn != NULL or SELECT * FROM MyTable WHERE …
SQL JOIN: what is the difference between WHERE clause and ON clause?
SQL INNER JOIN The SQL JOIN clause allows you to associate rows that belong to different tables. For instance, a CROSS JOIN will create a Cartesian Product containing all possible combinations of …
How do I perform an IF...THEN in an SQL SELECT?
2008年9月15日 · The CASE statement is the closest to IF in SQL and is supported on all versions of SQL Server.
SQL: IF clause within WHERE clause - Stack Overflow
2008年9月18日 · Is it possible to use an IF clause within a WHERE clause in MS SQL? Example: WHERE IF IsNumeric(@OrderNumber) = 1 OrderNumber = @OrderNumber ELSE OrderNumber …
sql - Copy data into another table - Stack Overflow
How to copy/append data from one table into another table with same schema in SQL Server? Edit: let's say there is a query select * into table1 from table2 where 1=1 which creates table1 wi...
sql - Concatenate text from multiple rows into a single text string ...
Consider a database table holding names, with three rows: Peter Paul Mary Is there an easy way to turn this into a single string of Peter, Paul, Mary?
Get the last day of the month in SQL - Stack Overflow
From SQL Server 2012 you can use the EOMONTH function. Returns the last day of the month that contains the specified date, with an optional offset. Syntax
SQL to find the number of distinct values in a column
2019年4月5日 · SQL to find the number of distinct values in a column Asked 17 years, 3 months ago Modified 2 years, 8 months ago Viewed 826k times