What is the difference between stored procedures and functions?

The differences between stored procedures and functions are: 1. A stored procedure is a precompiled collection of SQL statements and optional control flow statements, while a function is a subroutine composed of one or more SQL statements; 2. Stored procedures can execute a series of SQL statements in a single stored procedure, while custom functions have many restrictions; 3. Different execution methods.

The difference between stored procedures and functions

1. Different meanings

1. Stored procedures: A stored procedure is a precompiled collection of SQL statements and optional control flow statements that are stored with a name and processed as a unit.

2. Function: It is a subroutine composed of one or more SQL statements, which can be used to encapsulate code for reuse. There are many restrictions on functions. For example, temporary tables cannot be used, only table variables, etc.

2. Different usage conditions

1. Stored procedure: A series of SQL statements can be executed in a single stored procedure. . And you can reference other stored procedures from within your own stored procedures, which can simplify a series of complex statements.

2. Function: There are many restrictions on custom functions. Many statements cannot be used and many functions cannot be implemented. Functions can directly reference return values ​​and use table variables to return recordsets. However, user-defined functions cannot be used to perform a set of operations that modify the global database state.

3. Different execution methods

1. Stored procedure: Stored procedures can return parameters, such as record sets, while functions can only return values ​​or table objects. There are three types of parameters for stored procedures: in, out, and inout. There is no need for a return type when declaring a stored procedure.

2. Function: The function parameter only has in, and the function needs to describe the return type, and the function must contain a valid return statement.

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