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Counting DISTINCT over multiple columns
... function turns the ints into varchars to make the distinct more reliable
SELECT COUNT(DISTINCT (CHECKSUM(DocumentId,DocumentSessionId)) + CHECKSUM(REVERSE(DocumentId),REVERSE(DocumentSessionId)) )
FROM DocumentOutPutItems
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SQL SELECT WHERE field contains words
I need a select which would return results like this:
15 Answers
15
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MySQL ON DUPLICATE KEY - last insert id?
...LAST_INSERT_ID(3000)) ON DUPLICATE KEY UPDATE id = LAST_INSERT_ID(id + 1);
SELECT LAST_INSERT_ID();
If the prefix exists, it will increment it and populate last_insert_id.
If the prefix does not exist, it will insert the prefix with the value 3000 and populate last_insert_id with 3000.
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App Inventor 2 SQLite 拓展：超流行兼容主流SQL语法的迷你本地数据库引擎 ...
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SQLite 拓展
SQLite
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如何使用
背景
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方法
常规
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数据操作
绑定参数
案例
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Pandas groupby: How to get a union of strings
I have a dataframe like this:
8 Answers
8
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How to remove constraints from my MySQL table?
...an show the names of the foreign keys by using this query, as shown here:
SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE REFERENCED_TABLE_SCHEMA = '<database>' AND REFERENCED_TABLE_NAME = '<table>';
Then remove the foreign key by running the before mentioned DR...
Adding a public key to ~/.ssh/authorized_keys does not log me in automatically
...ider the excellent http://www.fail2ban.org
8. Extra
SSH tunnel to access a MySQL (bind = 127.0.0.1) server
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Display open transactions in MySQL
... the current transaction list in InnoDB with the query below if you want.
SELECT * FROM information_schema.innodb_trx\G
From the document:
The INNODB_TRX table contains information about every transaction (excluding read-only transactions) currently executing inside InnoDB, including whether t...
Dropping Unique constraint from MySQL table
...AINT unq_tab_id UNIQUE(id));
-- checking constraint name if autogenerated
SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE TABLE_NAME = 'tab';
-- dropping constraint
ALTER TABLE tab DROP CONSTRAINT unq_tab_id;
db<>fiddle demo
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How to reset AUTO_INCREMENT in MySQL?
... it will set NULL auto-inc value on information_schema; check SELECT AUTO_INCREMENT FROM information_schema.tables WHERE table_name = 'my_table' AND table_schema = DATABASE( ) ;
– K-Gun
Dec 5 '15 at 0:42
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