Detailed introduction to the steps to connect php to the database

This article briefly describes the steps to connect PHP to the database for reference only.

1: Link database

①Host address

②mysql username

③mysql password

④Select Connected database

⑤Port number

mysqli_connect($localhost, $user, $password, $port);

Return: If the connection is successful, the symbol of the resource type is returned; if the connection fails, false is returned.

If we establish more than one connection with mysql, then various functions that operate the database in the future must pass in the returned connection symbol;

If we establish only one connection with mysql, then There is no need to pass in this identifier for various functions that operate the database in the future. Suggestions are passed in.

2: Check whether the database connection is successful?

mysqli_connect_errno()andmysqli_connect_error()

##mysqli_connect_errno(); Returns the last database connection error The error number, the connection is successful and returns 0

mysqli_connect_error(); Returns the error message of the last database connection

3: Select the database

mysqli_select_db($conn, $dbname);

①Identifier

②Connection database name

If the connection is successful, return true; if the connection fails, return false

4: Set character set encoding Format

mysqli_select_charset($conn, $charset);

5. Write sql statement

Example:

$sql = "select * from table_name";

6. Execute sql statement

mysqli_query($conn, $sql);

If it is adding, deleting or modifying, a Boolean value will be returned. The number of rows affected by the last operation, if Yes query will be put back into the resource result set.

The above content is for reference only.

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