explain if statement

In front of you to explain a multi-choice ElseIf statement, although this statement can make a variety of judgments, but when used, need to write a lot of if statements, to our program readability inconvenience, in order to avoid the IF statement

Objective Process Control statement: In the process of executing a program, the order of execution of each statement has a direct effect on the result of the program. That is to say, the process of the program has a direct impact on the running

With the help of explain, you know when to add an index to the table to use the index to find records and make the select run faster.If some problems arise due to improper use of the index, you can run analyze table to update the table's statistics,

[MySQL Notes] SQL optimization tool-explain the output format of the explain command If you have experience using MySQL, you may encounter slow SQL queries in your project. In some scenarios, you can easily locate the problem (for example, when a

Mysql explain usage (use explain to optimize the query statement), mysqlexplain First, I will give a simple example and then explain the information in the explain column. Table 1: catefory document category table: Create table if not exists

The code we see earlier is executed sequentially, that is, the first statement is executed first, then the second, the third ... Until the last statement. However, in many cases, sequential structure of the code is far from enough, such as a

EXPLAIN is used to return a row of information for each table in the SELECT statement. Tables are listed in the order they will be read by MySQL during query processing. EXPLAIN is used to return a row of information for each table in the SELECT

Explain the process and sequence of Oracle SQL statement execution. Step 1: the client sends the statement to the server for execution When we execute an SQL statement on the client, the client sends the SQL statement to the server and allows the

The performance of SQL query statements affects the performance of the entire database to a certain extent. In many cases, poor database performance is almost caused by poor SQL statements. SQL statement executionThe Plan determines how the SQL

The explanation of mysql explain is clear.Of With the help of explain, you will know when to add an index to the table to use the index to search for records so that select can run faster.If the index is not properly used, you can run analyze table