Query类增加分表获取方法 支持不同的规则

library/think/db/Query.php

@@ -39,6 +39,8 @@ class Query
     protected $options = [];
     // 参数绑定
     protected $bind = [];
+    // 分表规则
+    protected $partition = [];
 
     /**
      * 架构函数
@@ -256,6 +258,62 @@ class Query
         return $this->connection->getConfig($name);
     }
 
+    /**
+     * 得到分表的的数据表名
+     * @access public
+     * @param array $data 操作的数据
+     * @return string
+     */
+    public function getPartitionTableName($data = [])
+    {
+        // 对数据表进行分区
+        if (isset($data[$this->partition['field']])) {
+            $field = $data[$this->partition['field']];
+            switch ($this->partition['type']) {
+                case 'id':
+                    // 按照id范围分表
+                    $step = $this->partition['expr'];
+                    $seq  = floor($field / $step) + 1;
+                    break;
+                case 'year':
+                    // 按照年份分表
+                    if (!is_numeric($field)) {
+                        $field = strtotime($field);
+                    }
+                    $seq = date('Y', $field) - $this->partition['expr'] + 1;
+                    break;
+                case 'mod':
+                    // 按照id的模数分表
+                    $seq = ($field % $this->partition['num']) + 1;
+                    break;
+                case 'md5':
+                    // 按照md5的序列分表
+                    $seq = (ord(substr(md5($field), 0, 1)) % $this->partition['num']) + 1;
+                    break;
+                default:
+                    if (function_exists($this->partition['type'])) {
+                        // 支持指定函数哈希
+                        $fun = $this->partition['type'];
+                        $seq = (ord(substr($fun($field), 0, 1)) % $this->partition['num']) + 1;
+                    } else {
+                        // 按照字段的首字母的值分表
+                        $seq = (ord($field{0}) % $this->partition['num']) + 1;
+                    }
+            }
+            return $this->getTable() . '_' . $seq;
+        } else {
+            // 当设置的分表字段不在查询条件或者数据中
+            // 进行联合查询，必须设定 partition['num']
+            $tableName = [];
+            for ($i = 0; $i < $this->partition['num']; $i++) {
+                $tableName[] = 'SELECT * FROM ' . $this->getTable() . '_' . ($i + 1);
+            }
+
+            $tableName = '( ' . implode(" UNION ", $tableName) . ') AS ' . $this->name;
+            return $tableName;
+        }
+    }
+
     /**
      * 获取当前的builder实例对象
      * @access protected