PHP 操作MYSQL基础知识

mysql_connect()
resource mysql_connect([string hostname [:port] [:/path/to/socket] [, string username] [, string password]])
示例：$conn = @mysql_connect("localhost", "username", "password") or dir("不能连接到Mysql Server");
使用该连接必须显示的关闭连接

建立数据库连接

mysql_pconnect()
resource mysql_pconnect([string hostname [:port] [:/path/to/socket] [, string username] [, string password]])
示例：$conn = @mysql_pconnect("localhost", "username", "password") or dir("不能连接到Mysql Server");
使用该连接函数不需要显示的关闭连接，它相当于使用了连接池

关闭数据库连接

mysql_close()
$conn = @mysql_connect("localhost", "username", "password") or die("不能连接到Mysql Server");
@mysql_select_db("MyDatabase") or die("不能选择这个数据库，或数据库不存在");
echo "你已经连接到MyDatabase数据库";
mysql_close();

选择数据库

mysql_select_db()
boolean mysql_select_db(string db_name [, resource link_id])
$conn = @mysql_connect("localhost", "username", "password") or die("不能连接到Mysql Server");
@mysql_select_db("MyDatabase") or die("不能选择这个数据库，或数据库不存在");

查询MySQL

mysql_query()
resource mysql_query (string query, [resource link_id])
$linkId = @mysql_connect("localhost", "username", "password") or die("不能连接到Mysql Server");
@mysql_select_db("MyDatabase") or die("不能选择这个数据库，或者数据库不存在");
$query = "select * from MyTable";
$result = mysql_query($query);
mysql_close();
若SQL查询执行成功，则返回资源标识符，失败时返回FALSE。若执行更新成功，则返回TRUE，否则返回FALSE

查询MySQL

mysql_db_query()
resource mysql_db_query(string database, string query [, resource link_id])
$linkId = @mysql_connect("localhost", "username", "password") or die("不能连接到MysqlServer");
$query = "select * from MyTable";
$result = mysql_db_query("MyDatabase", $query);
mysql_close();
为了使代码清晰，不推荐使用这个函数调用

获取和显示数据

mysql_result()
mixed mysql_result (resource result_set, int row [, mixed field])
$query = "select id, name from MyTable order by name";
$result = mysql_query($query);
$c_id = mysql_result($result, 0, "id");
$c_name = mysql_result($result, 0, "name");
最简单、也是效率最低的数据获取函数

获取和显示数据

mysql_fetch_row()
array mysql_fetch_row (resource result_set)
$query = "select id, name from MyTable order by name";
$result = mysql_query($query);
while (list($id, $name) = mysql_fetch_row($result)) {
        echo("Name: $name ($id) ");
}
函数从result_set中获取整个数据行，将值放在一个索引数组中。通常会结使list()函数使用

获取和显示数据

mysql_fetch_array()
array mysql_fetch_array (resource result_set [, int result_type])
$query = "select id, name from MyTable order by name";
$result = mysql_query($query);
while($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
        $id = $row["id"];
        $name = $row["name"];
        echo "Name: $name ($id) ";
}
result_type的值有：
MYSQL_ASSOC: 字段名表示键，字段内容为值
MYSQL_NUM: 数值索引数组，操作与mysql_fetch_ros()函数一样
MYSQL_BOTH: 即作为关联数组又作为数值索引数组返回。result_type的默认值。

获取和显示数据

mysql_fetch_assoc()
array mysql_fetch_assoc (resource result_set)
相当于调用 mysql_fetch_array(resource, MYSQL_ASSOC);

获取和显示数据

mysql_fetch_object()
object mysql_fetch_object(resource result_set)
$query = "select id, name from MyTable order by name";
while ($row = mysql_fetch_object($result)) {
        $id = $row->id;
        $name = $row->name;
        echo "Name: $name ($id) ";
}
在操作上与mysql_fetch_array()相同

所选择的记录

mysql_num_rows()
int mysql_num_rows(resource result_set)
#query = "select id, name from MyTable where id > 65";
$result = mysql_query($query);
echo "有".mysql_num_rows($result)."条记录的ID大于65";
只在确定select查询所获取的记录数时才有用。

受影响的记录

mysql_affected_rows()
int mysql_affected_rows([resource link_id])
$query = "update MyTable set name="CheneyFu" where id>=5";
$result = mysql_query($query);
echo "ID大于等于5的名称被更新了的记录数：".mysql_affected_rows();
该函数获取受INSERT,UPDATE或DELETE更新语句影响的行数

获取数据库列表信息

mysql_list_dbs()
resource mysql_list_dbs([resource link_id])
mysql_connect("localhost", "username", "password");
$dbs = mysql_list_dbs();
echo "Databases: ";
while (list($db) = mysql_fetch_rows($dbs)) {
        echo "$db ";
}

获取数据库名

mysql_db_name()
string mysql_db_name(resource result_set, integer index)
该函数获取在mysql_list_dbs()所返回result_set中位于指定index索引的数据库名

获取数据库表列表

mysql_list_tables()
resource mysql_list_tables(string database [, resource link_id])
mysql_connect("localhost", "username", "password");
$tables = mysql_list_tables("MyDatabase");
while (list($table) = mysql_fetch_row($tables)) {
        echo "$table ";
}该函数获取database中所有表的表名

获取数据库表名

mysql_tablename()
string mysql_tablename(resource result_set, integer index)
mysql_connect("localhost", "username", "password");
$tables = mysql_list_tables("MyDatabase");
$count = -1;
while (++$count         echo mysql_tablename($tables, $count)."";
}
该函数获取mysql_list_tables()所返回result_set中位于指定index索引的表名

获取字段信息

mysql_fetch_field()
object mysql_fetch_field(resource result [, int field_offset])
mysql_connect("localhost", "username", "password");
mysql_select_db("MyDatabase");
$query = "select * from MyTable";
$result = mysql_query($query);
$fields = mysql_num_fields($result);
for($count = 0; $count        $field = mysql_fetch_field($result, $count);
       echo "$field->name  $field->type  ($field->max_length) ";
}

返回的对象共有12个对象属性： name: 字段名 table: 字段所在的表 max_length: 字段的最大长度 not_null: 如果字段不能为null，则为1，否则0 primary_key: 如果字段为主键，则为1，否则0 unique_key: 如果字段是唯一键，则为1， 否则0 multiple_key: 如果字段为非唯一，则为1，否则0 numeric: 如果字段为数值则为1，否则0 blob: 如果字段为BLOB则为1，否则为0 type: 字段的数据类型 unsigned: 如果字段为无符号数则为1，否则为0 zerofill: 如果字段为“零填充”则为1， 否则为0

获取查询的字段数

mysql_num_fields()
integer mysql_num_fields (resource result_set)
$query = "select id, name from MyTable order by name";
$result = mysql_query($query);
echo "这个查询的字段数是：".mysql_num_fields($result)."";

返回查询result_set中的字段数

获取指定表的所有字段的字段名

mysql_list_fields()
resource mysql_list_fields (string database_name, string table_name [, resource link_id])
$fields = mysql_list_fields("MyDatabase", "MyTable");
echo "数据库MyDatabase中表MyTable的字段数： ".mysql_num_fields($fields)."";

获取指定的字段选项

mysql_field_flags()
string mysql_field_flags (resource result_set, integer field_offset)

获取指定的字段的最大长度

mysql_field_len()
integer mysql_field_len (resource result_set, integer field_offset)
$query = "select name from MyTable";
$result = mysql_query($query);
$row = mysql_fetch_row($result);
echo mysql_field_len($result, 0)."";
如果mysql_field_len($reseult, 0) = 16777215
那么numer_format(mysql_field_len($result))等于16,777,215

获取字段名

mysql_field_name()
string mysql_field_name (resource result_set, int field_offset)
$query = "select id as PKID, name from MyTable order by name";
$result = mysql_query($query);
$row = mysql_fetch_row($result);
echo mysql_field_name($result, 0); // Result: PKID

获取字段类型

mysql_field_type()
string mysql_field_type (resource result_set, int field_offset)
$query = "select id, name from MyTable order by name";
$result = mysql_query($query);
$row = mysql_fetch_row($result);
echo mysql_field_type($result, 0); // Result: int

获取字段所在表名

mysql_field_table()
string mysql_field_table (resource result_set, int field_offset)
$query = "select id as PKID, name from MyTable order by name";
$result = mysql_query($query);
$row = mysql_fetch_row($result);
echo mysql_field_table($result, 0);  // Result: MyTable