if statement in select query

Databases are people who exist to manage information more easily and efficiently, and want the database to provide the information they need at any time. Therefore, for the user, the data query is the data The most important function of the library. This chapter describes how to implement a data query. In a database, a data query is done through a

Php uses the select statement to implement mysql paging query bitsCN.com. using a feature of the select statement, you can easily implement paging of mysql Query results, the implementation process of this method is described in d

MySQL query page is a feature that we often need to implement. The following describes how to implement MySQL query page. I hope you can learn more about MySQL query pages. Using a feature of the select statement in mysql, you can easily implement MySQL

Using a feature of the SELECT statement, you can easily implement the paging of MySQL query results. The implementation process of this method is described in detail in the following sections. MySQL paging query is a common problem. How can this problem be achieved? The following describes how to implement MySQL pa

The most commonly used SELECT statement in SQL, which is used to select data in a table.The knowledge points to remember are as follows: SELECT Statement Format: SELECT the column name to

To query the content in the mysql database in php, we must first connect to the mysql database and then use SQL statements for query. Let's take a look at some examples. SQL has many statements for database operations. However, common and comparative statements are required. SELECT statements are used to SELECT data fr

Use the start with... connect by prior clause in the SELECT statement to implement recursive query Today, we found that the SELECT statement in Oracle can implement recursive queries using the start with... connect by prior clause. The connect by clause is used in structure

limit, when other servers execute the same SQL statement, they will automatically wait for the release lock. after the previous server lock is released, the server will be able to query the next 30 data records. If it is more intelligent, oracle supports for update skip locked to skip the lock area, so that the next 30 records can be queried immediately. Here we still need to talk about the deadlock caus

Recently there is a business requirement, multiple machines need to query data from a MySQL table at the same time and make subsequent business logic, in order to prevent multiple machines to get the same data at the same time, each machine needs to lock in the acquisition data segment, to ensure that multiple machines do not get the same data.Our MySQL storage engine is InnoDB and supports row locks. There are many ways to get data at the same time,

Mysql displays the query field name in the select statement. if a text input box is specified, how does one input the select query statement to return the field name in the select

Mysql paging query is a common problem. How can this problem be achieved? The following describes how to implement mysql paging query. Mysql uses a feature of the select statement to conveniently implement paging of query results. The se