sql set variable to null

1 Introduction to null valuesNULL is a unique data type in the database. If a column in a record is NULL, the value of this column is unknown and uncertain. Since it is unknown, there are several possibilities. Therefore, NULL is not a definite

SQL WHERE variable IS NULL causes full table scan ProblemsToday, when reviewing the stored procedures of the project, we found that there are a large number of statements to judge whether the variable is NULL in the condition, such:SET @ SQL =

When a field in the database is set to Null, the mobile phone will return Null by default. if I want the mobile phone to return Null, I have to make a judgment. 1. if I want to leave the returned result blank on the mobile phone, I will not make any

For more information about bugs fixed in SQL Server 2000 Service Pack 4, click the following article number to view the article in the Microsoft Knowledge Base:314128 FIX: When an RPC call is performed, Access with conflicting values includes an

Copy Code code as follows: SET @SQL = ' SELECT * Comment with (NOLOCK) WHERE 1=1 and (@ProjectIds is Null or ProjectID = @ProjectIds) and (@Scores is null or Score = @Scores) ' Remember, in the past when doing Oracle

Correct use and space occupation of NULL in SQL Server, servernull We often encounter NULL in the use or maintenance of SQL Server. What is NULL? The following is a brief description provided by MSDN (see "Null Values "): A value of NULL

Oracle SQL * plus is a client tool that interacts with oracle. In SQL * plus, you can run the SQL * plus command and the SQL * plus statement. The DML, DDL, and DCL statements we usually call are SQL * plus statements. After they are executed, they

Error message:An error occurred executing the SQL statement:/*!40111 SET [Email protected]_sql_notes */Error message: Variable ' sql_notes ' can ' t is set to the value of ' NULL 'Check:The error message is that sql_notes cannot be set to a null

Oracle SQL * plus is a client tool that interacts with oracle. In SQL * plus, you can run the SQL * plus command and the SQL * plus statement. The DML, DDL, and DCL statements we usually call are SQL * plus statements. After they are executed,

Determines whether a variable is null: IF (@VaribleName is NULL) Select a record for which the field value is null: WHERE column_name is NULL ISNULL () function: ISNULL (@VaribleName, ' defaultvalue ') ISNULL (column_name, ' Default Value ')