diff --git a/library/think/db/Builder.php b/library/think/db/Builder.php
index 232e7b16..69484ffe 100644
--- a/library/think/db/Builder.php
+++ b/library/think/db/Builder.php
@@ -442,8 +442,12 @@ abstract class Builder
                 list($table, $type, $on) = $item;
                 $condition               = [];
                 foreach ((array) $on as $val) {
-                    list($val1, $val2) = explode('=', $val, 2);
-                    $condition[]       = $this->parseKey($val1, $options) . '=' . $this->parseKey($val2, $options);
+                    if (strpos($val, '=')) {
+                        list($val1, $val2) = explode('=', $val, 2);
+                        $condition[]       = $this->parseKey($val1, $options) . '=' . $this->parseKey($val2, $options);
+                    } else {
+                        $condition[] = $val;
+                    }
                 }
 
                 $table = $this->parseTable($table, $options);
diff --git a/library/think/db/Query.php b/library/think/db/Query.php
index 2e37e1a3..ec37e49d 100644
--- a/library/think/db/Query.php
+++ b/library/think/db/Query.php
@@ -666,22 +666,25 @@ class Query
             $prefix = $this->prefix;
             // 传入的表名为数组
             if (is_array($join)) {
+                if (count($join) > 1) {
+                    $prefix = array_pop($join);
+                }
                 if (0 !== $key = key($join)) {
                     // 设置了键名则键名为表名，键值作为表的别名
                     $table = $key;
+                    if (false === strpos($table, '.')) {
+                        $table = $prefix . $table;
+                    }
                     $alias = array_shift($join);
                     $this->alias([$table => $alias]);
                     $table = [$table => $alias];
                 } else {
                     $table = array_shift($join);
+                    if (false === strpos($table, '.')) {
+                        $table = $prefix . $table;
+                    }
                 }
-                if (count($join)) {
-                    // 有设置第二个元素则把第二元素作为表前缀
-                    $table = (string) current($join) . $table;
-                } elseif (false === strpos($table, '.')) {
-                    // 加上默认的表前缀
-                    $table = $prefix . $table;
-                }
+
             } else {
                 $join = trim($join);
                 if (0 === strpos($join, '__')) {