COALESCE() --函数返回众多表达式中第一个非NULL 表达式的值 COL_LENGTH(<'table_name'>, <'column_name'>) --函数返回表中指定字段的长度值 COL_NAME( , <column_id>) --函数返回表中指定字段的名称即列名 DATALENGTH() --函数返回数据表达式的数据的实际长度 DB_ID(['database_name']) --函数返回数...
Using ISNULL() or COALESCE() is even worse (worse because the QO is able to make some assumptions if the underlying field is not nullable). Dynamic SQL side-steps this because you're able to only specify the criteria needed, leaving the QO a clean path to determine the best plan....
T-SQL 中某些函数可以看作是CASE的表达式缩写,如:ISNULL、COALESCE、IIF和CHOOSE,其中只有COALESCE*是标准的,后两个仅在2012版本中可以使用 2.5 同时操作 SELECT col1, col2 FROM dbo.test WHERE col1 <> 0 AND col2/col > 2 1. 这是一个col2/col1大于2的查询语句,很有可能假定SQL Server 会从左到右...
字符串长度 LENGTH DATELENGTH or LEN 列表中最大的字符串 GREATEST N/A 列表中最小的字符串 LEAST N/A 如果为NULL则转换字串 NVL ISNULL 日期函数 函数Oracle Microsoft SQL Server 日期相加 (date column +/- value) or ADD_MONTHS DATEADD 两个日期的差 (date column +/- value) or MONTHS_BETWEEN DA...
Checking if xp_cmdshell is enabled or not Chinese characters issue with T-SQL. Clear tempDB data CLR semaphore Clustered index update in execution plan Coalesce in JOIN condition Coalesce with Sum Code to check IBAN numbers? Collapse and Expand node in SQL editor not displaying Collate Database_...
cross apply ( select case when date1 >= coalesce(date2, date1) then date1 else date2 end as date12 ) as xa1; Explanation of Kent's solution:My solution uses a CROSS APPLY to provide re-use of a derived column "date12". Date12 is the greater of date1 and dat...
Null Dates in Sql/Tsql Order By Question: I have a table , order by coalesce(Image.UpdatedAt, Image.CreatedAt) In SQL, Server , you can also use Isnull() which is optimal if you only have, SELECT * FROM table WHERE ..., ELSE date END, date ; 9999- 12-31 is Maximum Date in...
他给的示例SQL如下： select HName,case when IsEnable=1 then '启用' else '停用' from tb_User ...
^ (位元排除 OR) ~ (位元 NOT) ^= (位元排除 OR EQUALS) |= (位元 OR EQUALS) &= (位元 AND EQUALS)函式@@DATEFIRST @@ERROR @@LANGUAGE @@SPID @@TRANCOUNT @@VERSION ABS ACOS ASCII ASIN ATAN ATN2 BINARY_CHECKSUM CASE CAST 和 CONVERT CEILING CHAR CHARINDEX CHECKSUM COALESCE COL_NAME ...
–3. 允许 显式 插入自增列：SET IDENTITY_INSERT TableName ON; 设置为ON后，允许当前回话对自增...