在MySQL中,LIMIT子句與SELECT語句一起使用,以限制結果集中的行數。 LIMIT子句接受一個或兩個offset和count的參數。這兩個參數的值都可以是零或正整數。
offset:用來指定要傳回的第一行的偏移量。
Count:用來指定要傳回的最大行數。
Limit子句接受一個或兩個參數,當指定兩個參數時,第一個參數是偏移量,第二個參數表示計數,而當只指定一個參數時,它表示從結果集開始傳回的行數。
LIMIT語法:
SELECT column1, column2, ... FROM table_name LIMIT offset, count;
如下表“Data”,其中包含三列“Firstname”、“Lastname”和“Age”。
要從「Data」表中擷取前三行,我們將使用下列查詢:
SELECT * FROM Data LIMIT 3;
要從「Data」表中擷取第2 -3行(包括),我們將使用以下查詢:
SELECT * FROM Data LIMIT 1, 2;
下面是PHP mysql實作查詢的程式碼範例:
範例1:Limit條件
#<?php $link = mysqli_connect("localhost", "root", "", "Mydb"); if ($link == = false) { die("ERROR: Could not connect. ".mysqli_connect_error()); } $sql = "SELECT * FROM Data LIMIT 2"; if ($res = mysqli_query($link, $sql)) { if (mysqli_num_rows($res) > 0) { echo "<table>"; echo "<tr>"; echo "<th>Firstname</th>"; echo "<th>Lastname</th>"; echo "<th>Age</th>"; echo "</tr>"; while ($row = mysqli_fetch_array($res)) { echo "<tr>"; echo "<td>".$row['Firstname']."</td>"; echo "<td>".$row['Lastname']."</td>"; echo "<td>".$row['Age']."</td>"; echo "</tr>"; } echo "</table>"; mysqli_free_result($res); } else { echo "No matching records are found."; } } else { echo "ERROR: Could not able to execute $sql. ".mysqli_error($link); } mysqli_close($link);
輸出:
#附註:「res」變數儲存函數mysql_query()傳回的資料。
每次呼叫mysqli_fetch_array()時,它都會從res()集中傳回下一行。
while迴圈用於遍歷表「data」的所有行。
範例2:使用物件導向方法的Limit子句
<?php $mysqli = new mysqli("localhost", "root", "", "Mydb"); if ($mysqli == = false) { die("ERROR: Could not connect. ".$mysqli->connect_error); } $sql = "SELECT * FROM Data LIMIT 2"; if ($res = $mysqli->query($sql)) { if ($res->num_rows > 0) { echo "<table>"; echo "<tr>"; echo "<th>Firstname</th>"; echo "<th>Lastname</th>"; echo "<th>Age</th>"; echo "</tr>"; while ($row = $res->fetch_array()) { echo "<tr>"; echo "<td>".$row['Firstname']."</td>"; echo "<td>".$row['Lastname']."</td>"; echo "<td>".$row['Age']."</td>"; echo "</tr>"; } echo "</table>"; $res->free(); } else { echo "No matching records are found."; } } else { echo "ERROR: Could not able to execute $sql. ".$mysqli->error; } $mysqli->close();
#輸出:
範例3:使用PDO方法的Limit子句
<?php try { $pdo = new PDO("mysql:host=localhost;dbname=Mydb", "root", ""); $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } catch (PDOException $e) { die("ERROR: Could not connect. ".$e->getMessage()); } try { $sql = "SELECT * FROM Data LIMIT 2"; $res = $pdo->query($sql); if ($res->rowCount() > 0) { echo "<table>"; echo "<tr>"; echo "<th>Firstname</th>"; echo "<th>Lastname</th>"; echo "<th>Age</th>"; echo "</tr>"; while ($row = $res->fetch()) { echo "<tr>"; echo "<td>".$row['Firstname']."</td>"; echo "<td>".$row['Lastname']."</td>"; echo "<td>".$row['Age']."</td>"; echo "</tr>"; } echo "</table>"; unset($res); } else { echo "No matching records are found."; } } catch (PDOException $e) { die("ERROR: Could not able to execute $sql. ".$e->getMessage()); } unset($pdo);
輸出:
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