mysql> alter table t1 -> alter check t1_chk_1 not enforced; Query OK, 0 rows affected (0.02 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> show create table t1\G *** 1. row *** Table: t1 Create Table: CREATE TABLE `t1` ( `c1` int DEFAULT NULL, `c2` int DEFAULT NULL, ...
MySQL>altertablet1 add iint;Query OK,0rows affected(0.41sec)Records:0Duplicates:0Warnings:0#然后再次执行sp,就会发现这次执行了这句SQL的prepare再进行execute。 MySQL>call p1;Query OK,0rows affected(34.24sec) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 1...
MySQL> alter table t1 add i int; Query OK, 0 rows affected (0.41 sec) Records: 0 Duplicates: 0 Warnings: 0 #然后再次执行sp,就会发现这次执行了这句SQL的prepare再进行execute。 MySQL> call p1; Query OK, 0 rows affected (34.24 sec)
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我们常见的数据库都实现了检查约束,例如 Oracle、SQL Server、PostgreSQL 以及 SQLite;然而 MySQL 一直以来没有真正实现该功能,直到最新的 MySQL 8.0.16。 MySQL 8.0.15 之前 在MySQL 8.0.15 以及之前的版本中,虽然 CREATE TABLE 语句允许CHECK (expr)形式的检查约束语法,但实际上解析之后会忽略该子句。例如 ...
One reason it can work on very large tables is that it divides each table into chunks of rows, and checksums each chunk with a single REPLACE..SELECT query. It varies the chunk size to make the checksum queries run in the desired amount of time. The goal of chunking the tables, instead...
in set (0.00 sec) mysql> create table B (id int, name varchar(20)); Query OK, 0 rows affected (0.02 sec) -- A与B表数据类型顺序对应,不需调整 mysql> insert into B select * from A; Query OK, 5 rows affected (0.01 sec) Records: 5 Duplicates: 0 Warnings: 0 mysql> select * ...
table: b type: ref possible_keys: ind_company_id key: ind_company_id key_len: 5 ref: sakila.a.company_id rows: 1 Extra: Usingwhere; Usingindex 2rowsinset(0.00 sec) 每个列的简单解释如下: select_type:表示 SELECT 的类型,常见的取值有 SIMPLE(简单表,即不使用表连接或者子查询)、PRIMARY(主...
mysql>alter table sc drop foreign key sc_ibfk_1; Query OK,0rows affected (0.03sec) Records:0Duplicates:0Warnings:0mysql>ALTER TABLE sc ADD CONSTRAINT sc_ibfk_1 FOREIGN KEY(sno) REFERENCES student(sno); Query OK,1row affected (0.15sec) ...
What to doCheck for duplicate field names and change the duplicates to distinct field names. Top of Page ACCWeb103079 Error textType mismatch in expression. What it meansThe types on either side of the join are incompatible or the field types compared are incompatible types. For example, ...