if statement in select query

Tags: selectall http User space result 1.0 sele character ttyPackage the SQL query statement "SELECT * from User" as a configuration file with MyBatis Define an XML mapping file, and the file name is known as the name. such as User-mapper.xml, the file contents are as follows: Public "-//mybatis.org//dtd Mapper 3.0//en" "Http://mybatis.org/dtd/mybatis-3-mapper.

9) DQL query statements are used in PL/SQL using the SELECT statement, which must be used as follows: Select ID into variable from t001 where id=5;Take the record field value out and assign a value to the variable. Tip: Select applies to cases where there are only one row of

Find an SQL query statement: select * fromTablewherABCDselect nbsp; * nbsp; from nbsp; Table nbsp; wher nbsp; A nbsp; and nbsp; B nbsp; and nbsp; C nbsp; and nbsp; D find an SQL query statement: select * from Table wher

In oracle, a select statement is used to list query results that meet multiple conditions. SELECT p. product_directory_level, COUNT (case when p. product_directory_level = 1 THEN 1 www.2cto.com else null end) material, COUNT (case when p. product_directory_level = 2 THEN 1 else null end) category, COUNT (case when p. p

-- Sum () Numeric (data type) Function Description: sums all non-null values in a specified Column -- AVG () Numeric (data type) Function Description: calculates the average value for all non-null values in the specified Column -- Min () number, character, date (data type) Function Description: returns the minimum number, minimum string, and earliest date and time in the specified column. -- Max () number, character, date (data type) Function Description: returns the maximum number, the maximum

The basic query operations in LINQ are the same as those in SQL, and for similarities and differences, let's look at the following:1) SelectGrammar:Description: The Select method itself is a generic collection extension method It acts on the ienumerable It only accepts one func Func 2) WhereGrammar:Description: The Where method is also a generic extension method It act

Request a SQL query statement: SELECT * from Table wher a B C D SELECT * from Table wher A and B and C and D Among them, A,b,c,d is the condition. How should it be constructed? is not to judge A,b,c,d, as long as there is a not empty, then the "where" And what about it? 》 ------Solution-------------------- Deter

operator. The query must meet two criteria at a time.2.or operator Query(1) Grammatical structureSelect * from where or Condition2(2) The OR operator is also a logical operator, called a logical OR operator, that meets one of the criteria when querying3.in operator Query(1) Grammatical structureSelect * from where column inch (value_list)Value_list represents

Environment: MySQL5.5 InnoDB Table post, the primary key is id The requirements are very simple, returned by ID post.name , need to return the specified number at one time, so used where id in : select `name` from `post` where `id` in(2142324,2106574,2106564,2075699,2065402,2050790,2038346,2038345,2035588,2031765,2022035,2022034,2020745,2020737,2020718,1987558,1970241,1962232,1911342,1891481,1889641,1877438,1877434,1867217,1866057,1866013,1847315); E

PHP Query Statement SELECT COUNT (*) from table where type= ' literary life '; How to output a result

To avoid table join queries, you need to add a field to the SQL statement results: The original SQL statement is: Select C. * From (select rownum as R, B. * From (select T ., T ., T ., T ., T ., t. user_id_encrypt, T ., t. create_time, T ., T ., T ., a. user_type from t_wi

SELECTt1.id, t1.order _ no, t1.order _ status, t1.pay _ status, t1.shipping _ status, t1.pay _ method, t1.invoice, t1.remark, t1.seller, t1.buyer, t1.site _ id, t1.order _ time, t1.pay _ time, t1.sign _ for_time, t1.delivery _ time, t1.subtotal, t1.freight, t1.invita... selectmysql data SQL optimization SELECT t1.id, t1.order _ no, t1.order _ status, t1.pay _ status, t1.shipping _ status,T1.pay _ method, t1.invoice, t1.remark, t1.seller, t1.buye

Note: The double and enclosed variables must be constant before query execution, for example, previous day Select a. billdate as fdate, max (Year (A. billdate) as fyear,Max (month (A. billdate) as fperiod, 'record' as fgroupid, '1' as fnumber,'2014. 02 'As faccountnum, 'waste paper goods (Project Accounting)' As faccountname,'RMB' as fcurrencynum, 'RMB' as fcurrencyname, sum (A. Total)As famountfor, sum (

SELECT statementThe core function of learning database is to master the use of commands such as adding, deleting, checking, and changing, in which query statements are the most complex and most important. This article focuses on the use of command related to query statements.There are three types of query statements: S

The number of MySQL query statistics implemented by single SELECT statement How is the use of a single SELECT statement to realize the number of MySQL query statistics? Use too much, such as a report card, you have to check the n

The query process for a SELECT statement by an Oracle database is shown in the following illustration: As we know from the above picture, There are three main steps: The client sends a SELECT statement to the server, the server executes the SQL

Label:When an UPDATE or DELETE statement contains a subquery, the table in the subquery cannot be in the update or DELETE statement, as if it contains runtime error, but when the SELECT statement contains a subquery, the table in the subquery can be in the SELECT statement.F

Oneexec While Read lineDo? InstructionsDoneMethod TwoCat File|while Read LineDo? InstructionsDoneMethod ThreeWhile Read lineDo? InstructionsDoneUntil syntaxUntil Do? directive:DoneNote: The condition will not be established, the execution of the cycle, the condition is set to stopFor syntax1 for variable name in variable listDo? directive:Done2 for ((EXP1;EXP2;EXP3))Do? directive:DoneDescriptionThe for is followed by 3 expressions, the first is the variable initialization, the second is the ran

Database paging query statement database query and database paging query statement Let's take a look at the paging SQL of a single SQL statement. Method 1: Applicable to SQL Server 2000/2005 S