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MySQL compatibility: show create database if not exists syntax #147

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lonng opened this issue Jan 3, 2019 · 0 comments
Closed

MySQL compatibility: show create database if not exists syntax #147

lonng opened this issue Jan 3, 2019 · 0 comments
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lonng commented Jan 3, 2019

See: https://dev.mysql.com/doc/refman/5.7/en/show-create-database.html

MySQL

MariaDB [(none)]> show create database b2;
+----------+----------------------------------------------------------------+
| Database | Create Database                                                |
+----------+----------------------------------------------------------------+
| b2       | CREATE DATABASE `b2` /*!40100 DEFAULT CHARACTER SET utf8mb4 */ |
+----------+----------------------------------------------------------------+
1 row in set (0.002 sec)

MariaDB [(none)]> show create database if not exists b2;
+----------+-----------------------------------------------------------------------------------------+
| Database | Create Database                                                                         |
+----------+-----------------------------------------------------------------------------------------+
| b2       | CREATE DATABASE /*!32312 IF NOT EXISTS*/ `b2` /*!40100 DEFAULT CHARACTER SET utf8mb4 */ |
+----------+-----------------------------------------------------------------------------------------+
1 row in set (0.000 sec)

TiDB

MySQL [b1]> show create batabase b2;
ERROR 1105 (HY000): line 1 column 20 near " b2" (total length 23)
MySQL [b1]> show create database b2;
+----------+-----------------------------------------------------------------+
| Database | Create Database                                                 |
+----------+-----------------------------------------------------------------+
| b2       | CREATE DATABASE `b2` /* !40100 DEFAULT CHARACTER SET utf8mb4 */ |
+----------+-----------------------------------------------------------------+
1 row in set (0.000 sec)

MySQL [b1]> show create database if not exists b2;
ERROR 1105 (HY000): line 1 column 23 near " not exists b2" (total length 37)
lonng added a commit to pingcap/tidb that referenced this issue Jan 4, 2019
…#8926)

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Thank you for contributing to TiDB! Please read TiDB's [CONTRIBUTING](https://github.com/pingcap/tidb/blob/master/CONTRIBUTING.md) document **BEFORE** filing this PR.
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### What problem does this PR solve? <!--add issue link with summary if exists-->

pingcap/parser#147
pingcap/parser#148

MySQL compatibility: `show create database if not exists` syntax

See: https://dev.mysql.com/doc/refman/5.7/en/show-create-database.html

MySQL

```
MariaDB [(none)]> show create database b2;
+----------+----------------------------------------------------------------+
| Database | Create Database                                                |
+----------+----------------------------------------------------------------+
| b2       | CREATE DATABASE `b2` /*!40100 DEFAULT CHARACTER SET utf8mb4 */ |
+----------+----------------------------------------------------------------+
1 row in set (0.002 sec)

MariaDB [(none)]> show create database if not exists b2;
+----------+-----------------------------------------------------------------------------------------+
| Database | Create Database                                                                         |
+----------+-----------------------------------------------------------------------------------------+
| b2       | CREATE DATABASE /*!32312 IF NOT EXISTS*/ `b2` /*!40100 DEFAULT CHARACTER SET utf8mb4 */ |
+----------+-----------------------------------------------------------------------------------------+
1 row in set (0.000 sec)
```

TiDB
```
MySQL [b1]> show create batabase b2;
ERROR 1105 (HY000): line 1 column 20 near " b2" (total length 23)
MySQL [b1]> show create database b2;
+----------+-----------------------------------------------------------------+
| Database | Create Database                                                 |
+----------+-----------------------------------------------------------------+
| b2       | CREATE DATABASE `b2` /* !40100 DEFAULT CHARACTER SET utf8mb4 */ |
+----------+-----------------------------------------------------------------+
1 row in set (0.000 sec)

MySQL [b1]> show create database if not exists b2;
ERROR 1105 (HY000): line 1 column 23 near " not exists b2" (total length 37)
```

### What is changed and how it works?

Insert `/*!32312 IF NOT EXISTS*/` before shema name when statement contains `if not exists`

### Check List <!--REMOVE the items that are not applicable-->

Tests <!-- At least one of them must be included. -->

 - Unit test

Code changes

Side effects

Related changes

 - Need to cherry-pick to the release branch

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This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/pingcap/tidb/8926)
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@lonng lonng closed this as completed Jan 4, 2019
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