sql update multiple rows

. Method Three: Using connection query Connection queries include: 1. Self-connect (join equals inner JOIN): Query result is data that exists on both sides 2. Left join to the left join: return all data on the right, return to the back, null not present 3. Right join: Return all data on the right, return on left, no null 4. Fully connected full join: Returns if one of the tables exists and the other does not exist as Nul [SQL]View PlainCopy

SQL statement Optimization-query different rows of the two tables NOT IN, NOT EXISTS, Join query Left Join, existsleft In actual development, we often need to compare the differences between two or more tables and compare the data that is the same and the data is different. At this time, we can use the following three methods: 1. IN or not in, 2. EXIST or NOTEXIST, 3. use join queries (inner join, left join

Tags: mysql optimized storageTypically, we use the following SQL statement to update field values:Copy CodeThe code is as follows:UPDATE mytable SET myfield= ' value ' WHERE other_field= ' other_value ';But what do you do if you want to update multiple rows of data, and each

SQL: insert all other columns of rows with the same primary key updated. In SQL writing, we often encounter such problems. During each insert operation, you must determine whether the data table already exists. For the same data, all the columns except the primary key are the same. If no data exists, the data is inserted. If yes, the data is updated. In this sit

Tags: drop order _id Post SQL query Space article tableDECLARE @D DATETIME set @d=getdate () set NOCOUNT on EXEC sp_msforeachtable @PRECOMMAND =n ' CREATE Table # # ( ID int IDENTITY, table name SYSNAME, number of fields int, number of records int, reserved Space NVARCHAR (), using Space VARCHAR (20) , Index uses space varchar (), unused space varchar () ', @COMMAND1 =n ' INSERT # # (table name, number of records, reserved space, use space, index u

Tags: strong SP on BS SQL table nbsp Server cPre-Preparation:CREATE TABLE Nums (X int);CREATE TABLE T (X int);GoPurpose: Insert the table Nums | Delete | The update is reflected in the T table.--------------------------------------------------------------------------------------------------------------- ------------------------------Insert:Insert into Nums (X)Output inserted. X #记得它在列表之后Into T (X)VALUES (1)

Update statements associated with multiple tables in MSSQL For example, table A has the following fields:Aid A1 A2 A3 A4Fields in Table B:Bid B1 B2 B3 B4 If you use all fields in Table B to update the corresponding fields in Table A, you can write the following in ms SQL Server:UpdateSet a1 = B. B1, a2 = B. B2, A3 =

The update in SQL implements Multi-Table update during development, and the database is switched back and forth, and some key syntaxes are different. This is a headache for developers. this article summarizes the usage of the Update statement in three databases: SQLServer, Oracle, and MySQL when updating

SQL is required. Note chapter 16th to update and insert data. SQL is required.16.1 update data To UPDATE (modify) The data in the table, you can use the UPDATE statement. UPDATE can be

WHERE Other_field (' other_values ') If the Where condition query out the ID of the record is not within the case range, MyField will be set to null. If you update multiple values, you need to modify them only slightly: UPDATE mytable SET myfield1 = case ID if 1 THEN ' Myvalue11 ' when 2 THEN ' Myvalue12 ' when 3 THEN ' Myva Lue13 ' End , myf

'+ident_incr('Student ') SQL returns the number of rows affected by the previous statement: @ @ROWCOUNT Returns the number of rows affected (insert, select, Delete, update): 1 Select * from where S_sex=' female ' 2 3Select @@ ROWCOUNT -- return 6 If the number of rows