Recent questions tagged SQL

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sql - Role of selectivity in index scan/seek

I have been reading in many SQL books and articles that selectivity is an important factor in creating index. If ... link to a relevant article? 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 - Select closest numerical value with MySQL query

This is probably easier than I am making it, but basically what I need to do is select the row that has ... , pick one of them randomly. 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 - How to iterate by row through a mysql query in php

Ok, So I am trying to query my database and select all rows that have a certain value. After that I turn the ... of data from the current row? 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 - Capturing multiple error messages from a single statement inside TRY CATCH

I am running a batch of statements on several columns and tables and want to retrieve information on what errors ... returns the second error) 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 - Retrieve Oracle last inserted IDENTITY

Since Oracle 12c we can use IDENTITY fields. Is there a way to retrieve the last inserted identity (i.e. ... LAST_INSERTED_ID() and so on)? 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 - Date serial in SQL?

How can I convert a day [1-31] and a month [1-12] and a year (all int), to a date serial IN SQL (without converting to varchar)? 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 - Check whether string is a date Postgresql

Is there any function in PostgreSQL that returns Boolean whether a given string is a date or not just like ISDATE( ... ISDATE("January 1, 2014") 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 - How to generate date series to occupy absent dates in google BiqQuery?

I am trying to get daily sum of sales from a google big-query table. I used following code for that. select ... on the month of the year 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 2005 - SQL: Aggregating strings together

In my SQL Server 2005 database, using an SLQ query, does anyone know the best way to group records together by ... 4 NULL Thanks for any help. 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 - Insert data and set foreign keys with Postgres

I have to migrate a large amount of existing data in a Postgres DB after a schema change. In the old ... an INSERT statement in Postgres SQL. 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 - Referencing current row in FILTER clause of window function

In PostgreSQL 9.4 the window functions have the new option of a FILTER to select a sub-set of the window ... to be based on window processing. 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 - Adding 'GO' statements to Entity Framework migrations

So I have an application with a ton of migrations made by Entity framework. We want to get a script for ... impossible to maintain every time. 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 - Entity Framework Skip/Take is very slow when number to skip is big

So, code is very simple: var result = dbContext.Skip(x).Take(y).ToList(); When x is big (~1.000.000) ... knows how to speed up such paging? 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 - Cannot SELECT from UPDATE RETURNING clause in postgres

I isolatet the problem from a much more complex query. Here the test scenario DROP TABLE test; CREATE TABLE ... with my initial statement? 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 - How to average time intervals?

In Oracle 10g I have a table that holds timestamps showing how long certain operations took. It has two timestamp ... i); RETURN numSecs; 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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sql - ERROR 1111 (HY000): Invalid use of group function

Given a staff table with the following attributes: ec,name,code,dob,salary List the staff members earning more than ... What is wrong with it? 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 - Finding rows that don't contain numeric data in Oracle

I am trying to locate some problematic records in a very large Oracle table. The column should contain all numeric ... call it on this column). 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 - Curious issue with Oracle UNION and ORDER BY

The following query is perfectly valid in pretty much every database (give or take a dual dummy table), including ... from the ORDER BY clause? 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 - Oracle Date TO_CHAR('Month DD, YYYY') has extra spaces in it

When I do... Select TO_CHAR (date_field, 'Month DD, YYYY') from... I get the following: July 01, 2011 ... just put them next to each 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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sql - Safest way to get last record ID from a table

In SQL Server 2008 and higher what is the best/safest/most correct way to retrieve the ID (based on ... FROM Table ORDER BY DESC)? 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 - Regular expression in PostgreSQL LIKE clause

I'm stuck with a simple regular expression. Not sure what I'm missing. A little rusty on regex skills. The expression ... : text) but it's NOT! 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 - How do I create a table alias in MySQL

I am migrating an MS Access application (which has linked tables to a MSSQL Server) to MySQL. As a means ... data from the customers 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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sql - Relation passed to #or must be structurally compatible. Incompatible values: [:references]

I have two queries, I need an or between them, i.e. I want results that are returned by either ... . Incompatible values: [:references] 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 - How to detect if a string contains special characters?

How to detect if a string contains special characters like #,$,^,&,*,@,! etc (non-alphanumeric characters) in 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 - ORA-01861: literal does not match format string

When I try to execute this snippet: cmd.CommandText = "SELECT alarm_id,definition_description,element_id, TO_CHAR ( ... with this statement? 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 - How do MySQL views work?

When I create a view I am basically making a new table that will automatically be transacted upon when data in ... use subqueries in my view? 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 - How to execute a stored procedure inside a select query

SELECT col1, col2, col3, EXEC GetAIntFromStoredProc(T.col1) AS col4 FROM Tbl AS T WHERE (col2 = @parm) How to ... SQL query in SQL Server 2008? 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 - Set Limit for a Table Rows In SQL

I want to set the limit for my table's rows. How can I do it? For example 50 rows in my 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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