大约有 3,551 项符合查询结果（耗时：0.0220秒） [XML]
How do I rename a column in a SQLite database table?
I would need to rename a few columns in some tables in a SQLite database.
I know that a similar question has been asked on stackoverflow previously, but it was for SQL in general, and the case of SQLite was not mentioned.
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Select statement to find duplicates on certain fields
Can you help me with SQL statements to find duplicates on multiple fields?
7 Answers
7...
SQL query to find record with ID not in another table
...d has a limited number of values cf : dba-oracle.com/t_maximum_number_of_sql_in_list_values.htm
– G.Busato
Feb 19 '18 at 11:04
2
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Liquibase lock - reasons?
...EQUENCE_NAME_SEQ"/>
</changeSet>
A work around is using plain SQL to check this instead:
<changeSet author="user" id="123">
<preConditions onFail="CONTINUE">
<sqlCheck expectedResult="0">
select count(*) from user_sequences where sequen...
Rails where condition using NOT NIL
... should use references here as well, otherwise you may end up with invalid SQL.
Foo.includes(:bar)
.references(:bar)
.merge(Bar.where.not(id: nil))
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Code-first vs Model/Database-first [closed]
...t
IMHO popular if you are designer fan (= you don't like writing code or SQL).
You will "draw" your model and let workflow generate your database script and T4 template generate your POCO entities. You will lose part of the control on both your entities and database but for small easy projects you...
IDENTITY_INSERT is set to OFF - How to turn it ON?
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Reminder
SQL Server only allows one table to have IDENTITY_INSERT property set to ON.
This does not work:
SET IDENTITY_INSERT TableA ON
SET IDENTITY_INSERT TableB ON
... INSERT ON TableA ...
... INSERT ON TableB ...
SET IDENTITY_INS...
When/Why to use Cascading in SQL Server?
When setting up foreign keys in SQL Server, under what circumstances should you have it cascade on delete or update, and what is the reasoning behind it?
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Grepping a huge file (80GB) any way to speed it up?
... command becomes:
LC_ALL=C fgrep -A 5 -B 5 'db_pd.Clients' eightygigsfile.sql
It will also be faster if you copy your file to RAM disk.
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Joins are for lazy people?
...ntly had a discussion with another developer who claimed to me that JOINs (SQL) are useless. This is technically true but he added that using joins is less efficient than making several requests and link tables in the code (C# or Java).
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