Use the mysql_query() function to execute SQL statements (PHP method 3 for operating MySQL database)

How PHP operates MySQL database-functions that execute SQL statements

In our daily PHP development work, when we want to When getting data from the database, after PHP connects to the database, the next step is to select the database. Then to operate the database table, we need to use SQL statements!

Recommended related mysql video tutorials: "mysql tutorial"

In the previous two articles "How to operate MySQL database with PHP - how to choose Database file ", "How to operate MySQL database with PHP - using the mysql_connect() function to connect to the database" introduces how to connect to the database and select the database, so today we will introduce how to execute SQL statements.

To operate on tables in the database, we usually use the mysql_query() function to execute SQL statements. The syntax format of this function is as follows:

mysql_query(string query[,resource link_identifier])

mysql_query() function is a special function of the instruction. All SQL statements are executed through it and the result set is returned.

Note:

The SQL statement executed in the mysql_query function should not end with a semicolon ";".

mysql_query() returns a resource identifier only for SELECT, SHOW, EXPLAIN or DESCRIBE statements, or FALSE if the query was executed incorrectly.

For other types of SQL statements, mysql_query() returns TRUE when executed successfully and FALSE when an error occurs.

A non-FALSE return value means the query is valid and can be executed by the server. This does not say anything about the number of rows affected or returned. It's possible that a query executed successfully but did not affect or return any rows.

Note:

The mysql_unbuffered_query() function sends a SQL query statement to MySQL, but does not obtain and cache the result set. It does not automatically obtain and cache the result set like the mysql_query() function. On the one hand, this will save considerable memory when processing large result sets. On the other hand, the result set can be operated immediately after obtaining the first row. , without waiting for the entire SQL statement to be executed.

The following uses the table tb_nember in the database as an example to illustrate the usage of common SQL statements.

For example, the code to execute a SQL statement to add member records is as follows:

$result = mysql_query("insert into tb_nember values('tm','111','tm@tmsoft')",$link);

For example, the code to execute a SQL statement to modify members is as follows:

$result = mysql_query("update tb_nember set user= '纯净水',pwd ='1025'where user = 'tm'",$link);

For example, to execute a The code of the SQL statement to delete member records is as follows:

$result = mysql_query("delete from tb_nember where user = '纯净水'",$link);

For example, the code to execute a SQL statement to query member records is as follows:

$result = mysql_query("select * from tb_nember",$link);

For example, to execute an SQL statement to display the structure of the member information table The code is as follows:

$result = mysql_query("DESC tb_nember");

Instructions:

Before executing the SQL statements listed above, you need to connect to the MySQL server and select The database and its implementation methods have been introduced in detail in the previous articles. Friends who don’t know can check it out. I won’t go into details here!

The above creates SQL statements through each instance and assigns them to the variable $result. PHP provides some functions to process the query result $result, such as mysql_fetch_array() function, mysql_fetch_object() function and mysql_fetch_row() function, etc. In order to let everyone understand these functions, we will start with the mysql_fetch_array() function below. , read specifically "How to operate MySQL database with PHP - use the mysql_fetch_array() function to obtain information in the array result set"!

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