Recent questions tagged SQL

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sql server - Good way to use table alias in Update statement?

Using SqlServer, and trying to update rows from within the same table. I want to use a table alias for ... there easier / better ways? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql server - SQL query to group by day

I want to list all sales, and group the sum by day. Sales (saleID INT, amount INT, created DATETIME) NOTE: I am using SQL Server 2005. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql - Efficient way of getting @@rowcount from a query using row_number

I have an expensive query using the row_number over() functionality in SQL Server 2005. I return only a ... love is @@ROW_NUMBERROWCOUNT :-) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql - What is the difference between cube, rollup and groupBy operators?

Question is pretty much in the title. I can't find any detailed documentation regarding the differences. I do ... I often grouped by. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql - Relationship of Primary Key and Clustered Index

Can a TABLE have a primary key without a clustered index? And can a TABLE have a clustered index without ... primary key and clustered index? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql - SQLite string contains other string query

How do I do this? For example, if my column is "cats,dogs,birds" and I want to get any rows where column contains cats? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql server - SQL Script to alter ALL Foreign Keys to add ON DELETE CASCADE

I have a SQL 2005 database with approx 250 tables. I want to temporarily enable ON DELETE CASCADE to all of ... and disables ON DELETE CASCADE? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql - MySQL 'create schema' and 'create database' - Is there any difference

Taking a peak into the information_schema database and peaking at the metadata for one of my pet projects, I'm ... as a database). Thanks! See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql server - CPU utilization by database?

Is it possible to get a breakdown of CPU utilization by database? I'm ideally looking for a Task Manager type ... to the sqlservr.exe CPU load. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql server - How to wait for 2 seconds?

How does one cause a delay in execution for a specified number of seconds? This doesn't do it: WAITFOR DELAY ' ... ; What is the correct format? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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407 views

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sql - Rails way to reset seed on id field

I have found the "pure SQL" answers to this question. Is there a way, in Rails, to reset the id field for ... the id field reset monthly or so. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql - What are the uses for Cross Join?

A cross join performs a cartesian product on the tuples of the two sets. SELECT * FROM Table1 CROSS ... an SQL operation particularly useful? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql - Why no many-to-many relationships?

I am learning about databases and SQL for the first time. In the text I'm reading (Oracle 11g: SQL by Joan Casteel) ... to ask why. :-) Thanks! See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql server - Can I loop through a table variable in T-SQL?

Is there anyway to loop through a table variable in T-SQL? DECLARE @table1 TABLE ( col1 int ) INSERT into ... Any help is greatly appreciated. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql - Postgresql query between date ranges

I am trying to query my postgresql db to return results where a date is in certain month and year. In other ... simpler way to do this? Thanks See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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219 views

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sql - MySQL GROUP BY two columns

I'm trying to group by multiple columns here - one on each table. It's a scenario where I want to find the ... .id ORDER BY total DESC LIMIT 30 See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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429 views

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sql server - Read committed Snapshot VS Snapshot Isolation Level

Could some one please help me understand when to use SNAPSHOT isolation level over READ COMMITTED SNAPSHOT in ... for SNAPSHOT isolation. Thanks See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql - When to use a View instead of a Table?

When should a View actually be used over an actual Table? What gains should I expect this to produce? Overall, ... like in the first place? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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321 views

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sql - How can I add a column that doesn't allow nulls in a Postgresql database?

I'm adding a new, "NOT NULL" column to my Postgresql database using the following query (sanitized for the ... the SQL from within Terminal. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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378 views

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sql - Mysql - How to quit/exit from stored procedure

I have very simple question but i did't get any simple code to exit from SP using Mysql. Can anyone share ... END IF; #proceed the code END; See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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243 views

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sql - How to select a record and update it, with a single queryset in Django?

How do I run an update and select statements on the same queryset rather than having to do two queries: ... value' where pk_field = some_value See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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288 views

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sql - How can I get the actual stored procedure line number from an error message?

When I use SQL Server and there's an error, the error message gives a line number that has no correlation to the ... I'm using SQL server 2005. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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295 views

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sql server - What is the PostgreSQL equivalent for ISNULL()

In MS SQL-Server, I can do: SELECT ISNULL(Field,'Empty') from Table But in PostgreSQL I get a syntax ... I emulate the ISNULL() functionality ? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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166 views

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sql - Why are foreign keys more used in theory than in practice?

When you study relational theory foreign keys are, of course, mandatory. But in practice, in every place I worked ... it for simplicity's sake. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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507 views

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sql - WITH (NOLOCK) vs SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

Could someone give me some guidance on when I should use WITH (NOLOCK) as opposed to SET TRANSACTION ISOLATION ... as opposed to the other? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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362 views

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sql server - "Prevent saving changes that require the table to be re-created" negative effects

Preamble I was modifying a column in SQL Server 2008 today, changing the datatype from something like currency(18, ... of the source table? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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222 views

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sql server - Stored procedures/DB schema in source control

Do you guys keep track of stored procedures and database schema in your source control system of choice? When ... than one "Accepted Answer"! See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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394 views

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sql - Storing DateTime (UTC) vs. storing DateTimeOffset

I usually have an "interceptor" that right before reading/writing from/to the database does DateTime conversion ( ... though. Any thoughts? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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