if statement in select query

into Select from statementThe statement form is: Insert into targer_table (field1,field2,...) Select Value1,value2,... from source_tableRequires that the target table targer_table must exist, because the target table targer_table already exists, so we can insert a constant in addition to inserting the field source_table the source table. Examples are as follows:

be duplicated only when all fields are the same; When the statement is select distinct stu_score, when the stu_score of the two data is the same, the two are considered to be duplicate; When the statement is select distinct stu_score and stu_name, the score and name must be the same before they are considered repeated

Fuzzy query in PHP and associate with three select boxes to fuzzy query select 1. in php, we often use drop-down boxes and associate them with each other. If there are many options in the drop-down box, we need to use the fuzzy search function. How can we do this? This function takes a detour. It is best not to associa

In order to make it easier for everyone to understand the SQL statement I cited, this article assumes that a student performance management database has been established, and the full text is described as an example of student performance management. 1. Display column names in query results: A. With AS keyword: select name as ' name ' from students B. Direct repr

Mysql statement to delete duplicate data, retain one; query all duplicate data; query duplicate data, mysql statement // Display all duplicate entries SELECT * FROM Table NameWHERE (Field 1, Field 2 ,...)IN (SELECT Field 1, Fiel

delete a corresponding relationship:Obj1 = press.objects.get (id = 2)Obj1.books.set (Book.objects.filter (id__in = [4, 5]))Obj1.books.remove (*book.objects.filter (id__in = [4, 5])) Press field set, null = True3. Associated fields:Find the publisher of the book of Happy baseobj = models. Press.objects.filter (id=models. Book.objects.get (title= ' Happy Camp '). press_id)Print (obj)obj = models. Press.objects.filter (books__title= ' Happy Camp '), #涉及到了一个连表查询, check oncePrint (obj)　　More than 3

Mandatory SQL statement (6) Data Query and SQL statement Data Query 1. Basic Query1) rename a columnSelect name as 'name' from Table name2) define constant ColumnsSelect = 'is 'From table name3) top usage: percent-- In this way, you can obtain the first 20% fields.Select top 20 percent * from Table Name4) Remove duplic

How to export MySQL Data Using the SELECT... into outfile statement: select... outfile The simplest way to export table data to a text file is to export the query results of the SELECT... into outfile statement directly to a file

Label:Logical query processing steps for the execution of the SELECT statement:(8) SELECT (9) DISTINCT(one) (1) From (3) (2) on (4) WHERE (5) GROUP by (6) with {CUBE | ROLLUP}(7) Having (10) ORDER by 1.FROM2.ON3.JOIN4.WHERE5.GROUP by6.WITH CUBE or with ROLLUP7.HAVING8.SELECT9.DISTINCT10.ORDER by11.TOPMicrosoft points o