Recent questions tagged SQL

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sql server - how to change the collate to all the columns of the database?

I would like to change the collation of all the columns of all the tables of my database. In stack overflow, ... tables in the database? Thanks. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql - How can I get a plain text postgres database dump on heroku?

Due to version incompatibilities of my postgres database on heroku (9.1) and my local installation (8. ... my_local_database -f my_dump_file.sql See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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sql - Why is there a HUGE performance difference between temp table and subselect

This is a question about SQL Server 2008 R2 I'm not a DBA, by far. I'm a java developer, who has to ... combined) took 2sec!!! What gives? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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237 views

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sql - in general, should every table in a database have an identity field to use as a PK?

This seems like a duplicate even as I ask it, but I searched and didn't find it. It seems like a good ... vs. natural keys) is also relevant. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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345 views

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sql - SQLite - replace part of a string

Is it possible using SQL in an SQLite table to replace part of a string? For example, I have a table ... bmp becomes c:anewfolderafilename.bmp ? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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486 views

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sql - MySQL very slow for alter table query

Why is it taking more than an hour to simply update this table to add a column? This table has 15M rows. It has 2 indexes ... ------+---------+ See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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309 views

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sql server - How can I tell if a database table is being accessed anymore? Want something like a "SELECT trigger"

I have a very large database with hundreds of tables, and after many, many product upgrades, I'm sure ... ORDER BY OBJECT_NAME(so.object_id) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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444 views

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sql server - How do you check if a certain index exists in a table?

Something like this: SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE CONSTRAINT_NAME =' ... indexes. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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275 views

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sql - How can I avoid NULLs in my database, while also representing missing data?

In SQL and Relational Theory (C.J. Date, 2009) chapter 4 advocates avoiding duplicate rows, and also to avoid ... know, you should use NULL). See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.6k views

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sql - Select multiple columns from a table, but group by one

The table name is "OrderDetails" and columns are given below: OrderDetailID || ProductID || ProductName || ... of the OrderQuantity column. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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287 views

1 answer

sql - Add primary key to existing table

I have an existing table called Persion. In this table I have 5 columns: persionId Pname PMid Pdescription Pamt ... 1000 records in the table) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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304 views

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sql - From a Sybase Database, how I can get table description ( field names and types)?

I have access to command line isql and I like to get Meta-Data of all the tables of a given database, ... How I can achieve that? Thanks. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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260 views

1 answer

sql - Using group by and having clause

Using the following schema: Supplier (sid, name, status, city) Part (pid, name, color, weight, city) ... Group By and Having clause works See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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562 views

1 answer

sql server - What do the different RAISERROR severity levels mean?

My best google result was this: below 11 are warnings, not errors 11-16 are available for use above 16 are ... and how they should be used? See Question&Answers more detail:os...