What are the commonly used functions in SQL statements and string functions commonly used in SQL sta

Commonly used string functions are:1. Character conversion function1、ascii()

2、char()

3. lower() and upper().

4、str()

2. Spacespace function1. ltrim() removes the space in the head of the string.

2. rtrim() removes the space at the end of the string.

3. Take the substring function1、left()

2、right()

3、substring()

4. String comparison function1、charindex()

2、patindex()

5. String operation functions1、quotename()

2、replicate()

3、reverse()

4、replace()

4、space()

5、stuff()

6. Data type conversion function1、cast()

2、convert()

7. Date function1、day(date_expression)2、month(date_expression)3、year(date_expression)4、dateadd()

5、datediff()

6、datename()

7、datepart()

8、getdate()

1. function is a function of SQL.

is a subroutine made up of one or more transact-sql statements that can be used to encapsulate for reuse. Instead of restricting users to built-in functions that are defined as part of the Transact-SQL language, Microsoft SQL Server allows users to create their own user-defined functions.

You can use the create function statement to create, the alter function statement to modify, and the drop function statement to remove user-defined functions. Each perfectly valid user-defined function name (database must be unique.

You must be granted the Create Function permission to create, modify, or delete user-defined functions. Before a user who is not the owner can use a function in a transact-sql statement, the user must first be granted the appropriate permissions to the function. To create or change a table that references a user-defined function in a check constraint, a default clause, or a calculated column definition, you must also have references permission on the function.

In a function, the differential handling causes a transact-sql error that results in the deletion of the statement and the continuation of the next statement in a pattern such as a trigger or stored procedure. In a function, the above error causes the function to stop executing. The next action causes the statement that stops waking up the function call.

The type of the user-defined function.

Maybe it's a function name named function!

Not at all! That's in PL SQL, it's fuction! Is the landlord mistaken?