If Statement Function

SQL used to manipulate the database is generally divided into two kinds, one is the query, which is what we call the SELECT statement, the other is to update the statement, also known as data manipulation statements. The implication is to modify the data. There are 3 statements in the standard SQL, which are INSERT, UPDATE, and DELETE. There is another REPLACE statement in MySQL, so this article uses MySQL as a background to discuss how to make updates in SQL. First, INSERT and REPLACE I ...

The complete collection of SQL statement operations deserves to be permanently stored the following statements are part of the MSSQL statement and are not available in Access. SQL classification: ddl-data Definition language (create,alter,drop,declare) dml-Data Manipulation Language (Select,delete,update,insert) dcl-Data Control Language (Grant,revoke, Commit,rollback first, briefly introduce the basic statement: 1, Description: Create number ...

MySQL database sql statement commonly used optimization methods 1. Query optimization, should try to avoid full table scan, should first consider where and order by the columns involved in the establishment of the index. 2. Should be avoided in the where clause on the field null value judgment, otherwise it will cause the engine to abandon the use of indexes and full table scan, such as: select id from t where num is null You can set the default value of num 0, to ensure that Num column table does not null value ...

SELECT DATA FROM A DATABASE TABLE A SELECT statement is used to select data from a database. Syntax SELECT column_name (s) FROM table_name Note: SQL statements are not case-sensitive. SELECT and select equivalent. In order for PHP to execute the above statement, we must use the mysql_query () function. This function is used to send queries or commands to MySQL. Example The following example selected stored in "Pers ...

Insert data into the database table The INSERT INTO statement is used to add a new record to the database table. Syntax INSERT INTO table_name VALUES (value1, value2, ....) You can also specify the column in which you want to insert data: INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ....) Note: SQL statements on ...

To select the data that matches the specified criteria, add the WHERE clause to the SELECT statement. WHERE clause To select the data that match the specified criteria, add a WHERE clause to the SELECT statement. Syntax SELECT column FROM table WHERE column operator value The following operators can be used with the WHERE clause: Operator Description = Equal! = Not equal> Greater than <...

This article introduces a MySQL batch intercept the last separated part of the SQL statement to another field to have a friend in need of reference. --field images saved data is: A.jpg;b.jpg;c.jpg to the images of the last picture c.jpg assignment to Images_default execution of the SQL statement is the code as follows UPDATE product SET ' Image_ Default ' = REVERSE ...

Update data in the database The UPDATE statement is used to modify data in a database table. Syntax UPDATE table_name SET column_name = new_value WHERE column_name = some_value Note: SQL is case insensitive. UPDATE and update equivalent. In order for PHP to execute the above statement, we must use mysql_query (function. This function is used to SQL ...

Delete data in the database DELETE FROM statement is used to delete records from the database table. Syntax DELETE FROM table_name WHERE column_name = some_value Note: SQL is case insensitive. DELETE FROM equivalent to delete from. In order for PHP to execute the above statement, we must use mysql_query (function. This function is used to send queries and SQL connections ...

According to today's Millet issued a statement said the application store will be a full line of 360 products to rectify the matter, 360 the company immediately released a response said, 360 mobile phone assistants just identify unnecessary pre-installed software, users can according to their own needs, choose to uninstall what does not need pre-installed software, there is no specific recommended uninstall situation.   　　All uninstall behavior, the user actively choose to implement. The following is the 360 statement: 360 statement: 360 Mobile phone helper help users uninstall pre-installed software, remove cowhide ...