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法律學MySQL 命令列工具：如何找到受 DELETE 影響的行數？
為此，你可以在末尾使用 row_count()。我們首先建立一個表 -
mysql> create table rowAfftectedByDeleteDemo -> ( -> CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> CustomerName varchar(20) -> ); Query OK, 0 rows affected (0.86 sec)
使用 insert 命令在表中插入一些記錄。查詢如下 -
mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('John');
Query OK, 1 row affected (0.14 sec)
mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('Carol');
Query OK, 1 row affected (0.10 sec)
mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('Bob');
Query OK, 1 row affected (0.09 sec)
mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('Sam');
Query OK, 1 row affected (0.09 sec)
mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('David');
Query OK, 1 row affected (0.08 sec)
mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('Maxwell');
Query OK, 1 row affected (0.09 sec)
mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('Ramit');
Query OK, 1 row affected (0.08 sec)
mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('James');
Query OK, 1 row affected (0.10 sec)使用 select 語句顯示錶中的所有記錄。查詢如下 -
mysql> select *from rowAfftectedByDeleteDemo;
以下是輸出 -
+------------+--------------+ | CustomerId | CustomerName | +------------+--------------+ | 1 | John | | 2 | Carol | | 3 | Bob | | 4 | Sam | | 5 | David | | 6 | Maxwell | | 7 | Ramit | | 8 | James | +------------+--------------+ 8 rows in set (0.00 sec)
在從表中刪除行之前，row_count() 的值為如下 -
mysql> select row_count();
以下是輸出 -
+-------------+ | row_count() | +-------------+ | -1 | +-------------+ 1 row in set (0.00 sec)
以下是從表中刪除行的查詢 -
mysql> delete from rowAfftectedByDeleteDemo where CustomerId =3 || CustomerId =4 || CustomerId =5 || CustomerId =6; Query OK, 4 rows affected (0.13 sec)
從表中刪除行後，row_count() 的值為如下 -
mysql> select row_count();
以下是輸出 -
+-------------+ | row_count() | +-------------+ | 4 | +-------------+ 1 row in set (0.00 sec)
更新日期： 2019-07-30
545 次瀏覽
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