sql not null constraint

Sometimes the following error occurs when you create a SQL Server job with an SQL statement: MSG 515, Level 16, State 2, procedure sp_add_job, line 137th Cannot insert value NULL into column ' owner_sid ', table ' msdb.dbo.sysjobs '; column does not allow null values. INSERT failed. Statement has been

Okay, maybe this was lame, but when I ' ve been away from writing SQL database queries for a while I can never remember how T o Search for database table fields, is either null, or NOT NULL. I always try to use the = operator or something else.So, for your Al, here's how to perform a SQL query and the Find all records

Tags: tab har ble col char ref SQL Server target sizeTransferred from: http://www.maomao365.com/?p=6965Summary:Here are two ways to share a null value in a field with a specified value, as follows:Lab environment: SQL Server R2 Cases:Create TableTest (keyIdint Identity, infovarchar( -))GoInsert intoTest (Info)Values('a'),('b'),(

determine whether it is the length of zero is the field is empty! So the code changes to this: Select * from where = NULL and datalength (Resultremarks) = 0 And there was nothing, and this time we looked at the data. It is found that the null value ZAI the database has a special meaning, which is different from the field containing 0, an empty string, or simply containing a space. So to determine whethe

The drop TABLE command is used to delete a table or all rows in a table. The syntax format is: drop TABLE "TableName" Here's an example: drop table employee; To delete the entire table (including all rows), you can use the drop TABLE command to add tablename. The drop TABLE command is not the same as deleting all records in a table: Tip "Cannot delete object ' Orders ' because the object is being referenced by a FOREIGN key constraint" because

Procedure Querylacklonorlattdcell (I_region_name varchar2, i_state varchar2) isbegin Select Region_name, state From gc3_td_site_history where 1 = 1 and region_name = decode (i_region_name, NULL, Region_name, i_ Region_name) and InStr (decode (i_state, NULL, State, i_state), state) > 0;end;If I_region_name is null, all region_name are queried

Transfer from http://www.cnblogs.com/longhs/p/3670307.htmlThere are five types of constraints in SQL Server, Primary key constraints, Foreign key constraints, Unique constraints, Default constraints, and Check c12> constraints, use SQL Server2008 today to demonstrate how these constraints are created and used. 1 . Primary Key constraint There is often a combin

bigint No Calendarquartername nvarchar (30) No CalendarYear bigint No CalendarYearName nvarchar (30) No Fiscalmonthname nvarchar (30) No Fiscalmonthofyear bigint No Fiscalquarter bigint No Fiscalquartername nvarchar (30) No

Label:The following code has been found on the Internet:DECLARE @Pk varchar (100);Select @Pk =name from sysobjects where parent_obj=object_id (' table name ') and xtype= ' Pk ';If @Pk is not nullBeginEXEC (' Alter table name Drop ' + @Pk)--Delete the primary keyEndThe point here is that the table Sysobjects,sysobjects table is a system table, each object created in the database (constraints, defaults, logs, rules, stored procedures, etc.) in the table for a row, the above xtype is the type, such

SQL uses three-valued predicate logic, so the result returned by a logical expression can be true, false, or unknown, and returning true in the three-value logic is not exactly the same as not returning false.SQL handling of query filtering conditions: Accept Ture deny false and unknownSQL handling of CHECK constraints: Accept FALSE deny TRUE and UNKnown the subtlety of unknown is when it is reversed results are still unknown ,

To prevent some of the filling is not filled:One, non-null constraintscannot be null.Action: Remove the check box in "Allow null values" in the table's design interface.Second, the default value.If you do not assign a value to the column, it will be filled with the default value.Action: In the table's design interface, select the appropriate column in the property panel below--default valueFor example, sele

It means you have duplicate records in your data.Two cases1. Existing tables and duplicates to import dataThis can be done by establishing an association between two tables, and the primary key cascade to find duplicate records2. Duplicate records exist in the table to be importedDuplicate records in a table can be identified by a statement similar to the followingSelect Studentcode from Studentscore GROUP by studentcode[here is the PRIMARY KEY field] having count (*) >1Then you can delete the d

Tags: http int add right-click End test exist BSP alterModify a Check constraint using the SSMS database management tool1, open the database, select Data table-Right click-"SELECT Design (or expand the constraints, select the constraints, right-click, select Modify, the following steps are the same).2. Select the data column to modify-Right click-select Check constraint.3. In check

· What is a database?The warehouse where the data is stored.· What is the difference between a database and a data structure?To solve the problem of manipulating data in memory, the database should solve the problem of manipulating data in the hard disk. Data structures study some abstract data models (ADT) and some of the operations defined on the model, the database is composed of tables, relationships, operations.· What is a primary key?The primary key is used to identify the uniqueness of th

Tags: os SP data BS Database SQL nbsp Table method1.DataTable DT; Assuming the field is name, DT has saved the datadt.rows[0]["name"] = = System.DBNull.Value; Determines whether the name field of the first row of data is empty2.DataTable DT; Assuming the field is name, DT has saved the datadt.rows[0]["Name"]. ToString () = = ""; Determines whether the name field of the first row of data is empty3.DataTable DT; Assuming the field is name, DT has saved

constraint, deleteIFEXISTS (SELECT*FromsysobjectsWHERE Name=' Pk_stuno 'and Xtype=' PK ')Alter TABLE StuinfoDrop Constraint Pk_stunoGo--Re-add the primary KEY constraint Pk_stunoALTER TABLE StuinfoADD CONSTRAINT Pk_stunoPRIMARY KEY(Stuno)Go--Example 3 to add a unique UQ constraint