Recent questions tagged database

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database - Effective strategy for leaving an audit trail/change history for DB applications?

What are some strategies that people have had success with for maintaining a change history for data in a fairly ... set Using PostgreSQL 8.x See Question&Answers more detail:os...

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

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database - Difference between NOW(), SYSDATE() & CURRENT_DATE() in MySQL

What difference between NOW() , SYSDATE() , CURRENT_DATE() in MySQL and where it can be used in real scenario ... are given same date and time. See Question&Answers more detail:os...

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

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database - Difference between a statement and a query in SQL

I still live in this ambiguity: conceptually what's the difference between a statement and a query in SQL? Can ... edit his answer. Many 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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database - Map items of collection snapshot in Firebase Firestore

Firebase Firestore Guides show how to iterate documents in a collection snapshot with forEach: db.collection("cities"). ... I map the snapshot? See Question&Answers more detail:os...

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

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database - Row count of a column family in Cassandra

Is there a way to get a row count (key count) of a single column family in Cassandra? get_count can only be used ... Each user is it's own row. See Question&Answers more detail:os...

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

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database connection - PostgreSQL: Warning: Console code page (437) differs from Windows code page (1252)

Using PostgreSQL when I connect to a db using c testdb inside PostgreSQL Database SQL Prompt. I successfully connect to ... ? How to resolve it? See Question&Answers more detail:os...

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

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database - Conditional INSERT INTO statement in postgres

I'm writing a booking procedure for a mock airline booking database and what I really want to do is something ... user interaction in this step? See Question&Answers more detail:os...

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

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database - Adding a column as a foreign key gives ERROR column referenced in foreign key constraint does not exist

I have the following set up, CREATE TABLE auth_user ( id int PRIMARY KEY ); CREATE TABLE links_chatpicmessage (); I ... exist How do I fix this? See Question&Answers more detail:os...

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

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database - Evaluating HDF5: What limitations/features does HDF5 provide for modelling data?

We are in evaluating technologies that we'll use to store data that we gather during the analysis of C/C++ code ... for the data? Many 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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database - SQL for Opening Hours

In my shops database I need to have the opening hours. Do you have an idea how i can implement this in my dB? The ... :00-12:00, 16:00-19:00) See Question&Answers more detail:os...

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

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database - Primary Key versus Unique Constraint?

I'm currently designing a brand new database. In school, we always learned to put a primary key in each table. I ... What's your point of view? See Question&Answers more detail:os...

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

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database - PGError: ERROR: permission denied for relation (when using Heroku)

I've recently gone through the database migration process as outlined here: https://devcenter.heroku.com/articles/migrating- ... do to fix it? See Question&Answers more detail:os...

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

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737 views

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database - How do I remove keys?

I want to remove keys that match "user*". How do I do that in redis command line? See Question&Answers more detail:os...

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

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804 views

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database - One-to many relationships in ER diagram

I am trying to show the following in the ER diagram: There are instructors and courses, a course is taught by ... we decide this? Thank you. See Question&Answers more detail:os...

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

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852 views

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database - Atomic operations in Django?

I'm trying to implement (what I think is) a pretty simple data model for a counter: class VisitorDayTypeCounter(models ... do I do this safely? See Question&Answers more detail:os...

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

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database - How to tag a changeset in liquibase to rollback

I have configured the maven pluggin for liquibase as specified in maven configuration. Now created a changeset like ... the changeset 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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database design - Sql Data Type for Primary Key - SQL Server?

Which sql data type should we use for number bases primary key: int bigint numeric float See Question&Answers more detail:os...

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

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836 views

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database - What is the biggest ID number that autoincrement can produce in mysql

I have an database that is rapidly filled with data we talk about 10-20k rows per day. What is a limit of an ... like to hear them. Thank you. See Question&Answers more detail:os...

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

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840 views

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database - How to remove foreign key constraint in sql server?

I want to remove foreign key from another table so i can insert values of my choice. I am new in databases ... drop or remove foreign key value. See Question&Answers more detail:os...

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

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842 views

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database - In a join table, what's the best workaround for Rails' absence of a composite key?

create_table :categories_posts, :id => false do |t| t.column :category_id, :integer, :null => false t.column ... there is a more elegant answer. See Question&Answers more detail:os...

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

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database design - What tag schema(s) are the most efficient/effective?

http://tagging.pui.ch/post/37027745720/tags-database-schemas Stackoverflow's tag handling is among the best ... have successfully implemented. See Question&Answers more detail:os...

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

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database - Hibernate @OneToMany remove child from list when updating parent

I have the following entities: TEAM @Entity @Table public class Team { [..] private Set<UserTeamRole> ... is appreciated. Thank you See Question&Answers more detail:os...

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

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738 views

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database - How can I add comments in MySQL?

I want to add comment in SQL code. How can I do this? I'm using MySQL. See Question&Answers more detail:os...

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

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686 views

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database design - How to understand the 5th Normal Form?

I'm using two online sources for gaining an understanding of the 5NF, without any rigor of Math and proofs. ... ? Could somebody please clarify? See Question&Answers more detail:os...

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

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985 views

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database - MySQL enum vs. set

For MySQL Data type of "enum" and "set" what are the differences and advantages and disadvantages of using ... multiple values to be selected. See Question&Answers more detail:os...

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

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960 views

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database design - What is the difference between 3NF and BCNF?

Can someone please explain the difference between 3NF and BCNF to me? It would be great if you could also provide some examples. 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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816 views

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database design - SQL Server: how to constrain a table to contain a single row?

I want to store a single row in a configuration table for my application. I would like to enforce that ... enforce the single row constraint ? See Question&Answers more detail:os...

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

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671 views

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database design - Anatomy of a Distributed System in PHP

I've a problem which is giving me some hard time trying to figure it out the ideal solution and, to better ... depending on the R(D)DBMS. See Question&Answers more detail:os...

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

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