Recent questions tagged Database

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I have two fields: one to store an excerpt with a max size of 500 characters, and another to store a ... description field as it's larger. 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 - Does dropping a table in MySQL also drop the indexes?

It's not explicitly mentioned in the documentation (http://dev.mysql.com/doc/refman/6.0/en/drop-table. ... table, and that seemed unnecessary. See Question&Answers more detail:os...

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

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689 views

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database - What exactly is a foreign key?

Ok. So I know what a primary key in DB is. If you have a table in a database, a primary key is a ... value in the table I am referring to? See Question&Answers more detail:os...

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

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675 views

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database - how B-tree indexing works in mysql

When I create an index for a table in mysql, I see that the index_type is type BTREE. Now although I ... does the database extract the record? See Question&Answers more detail:os...

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

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749 views

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database - SQLite 3 C API Transactions

I am using SQLite3 for iPhone development and I'm attempting to wrap a few insert statements into a transaction. ... ? Thanks for your help. See Question&Answers more detail:os...

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

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851 views

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database - Android SQLite: Which query ("query" or "rawQuery") is faster?

I am developing one android database application . I just want to know which code execute faster and what is the ... , null, null, 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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956 views

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database - How to fix a collation conflict in a SQL Server query?

I am working on a view, wherein I am using an inner join on two tables which are from two different ... material for these concepts is welcome. See Question&Answers more detail:os...

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

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660 views

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database - Mysql - Add auto_increment to primary key

I have a strange problem with mysql. I am trying to alter a table's column which is a primary key ... unsigned NOT NULL AUTO_INCREMENT, 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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691 views

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database - Avoiding PostgreSQL deadlocks when performing bulk update and delete operations

We have a single table which does not have references to any other tables. ... particular order? 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 connect MySQL Workbench to Amazon RDS?

I am accessing the Amazon RDS (MySQL) from Putty. MySQL Workbench works through SSH commandline only, but I ... directly from MySQL Workbench. See Question&Answers more detail:os...

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

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674 views

1 answer

database - How do I avoid a memory leak with LINQ-To-SQL?

I have been having some issues with LINQ-To-SQL around memory usage. I'm using it in a Windows Service ... that the memory is released? See Question&Answers more detail:os...

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

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778 views

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database - Rails Migration to convert string to integer?

Is it possible to change a field that's a string to an integer without clearing the data already entered? ... already entered. Thanks, Danny See Question&Answers more detail:os...

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

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678 views

1 answer

database design - MySQL "good" way to insert a row if not found, or update it if it is found

Very often, I want to run a query on one of my users where I want a row stored and associated with that user ... so often? Thanks for any help! See Question&Answers more detail:os...

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

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779 views

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database - What are PostgreSQL RULEs good for?

Question I often see it stated that rules should be avoided and triggers used instead. I can see the danger in ... for why this is bad design. See Question&Answers more detail:os...

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

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655 views

1 answer

database - Android Unit Tests Requiring Context

I am writing my first Android database backend and I'm struggling to unit test the creation of my database. ... should be an easier way. See Question&Answers more detail:os...

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

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692 views

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database design - Guid Primary /Foreign Key dilemma SQL Server

I am faced with the dilemma of changing my primary keys from int identities to Guid. I'll put my problem straight ... of your thoughts on 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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590 views

1 answer

database design - MySQL friends table

I have a MySQL DB in which I store data about each user. I would like to add a list of friends for each user. ... DB or is there a better way? See Question&Answers more detail:os...

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

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638 views

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database - Android - Is ViewHolder pattern automatically implemented in CursorAdapter?

I always use ViewHolder pattern in my custom ArrayAdapter classes. However, in CursorAdapter the getView() ... support.v4.widget.CursorAdapter See Question&Answers more detail:os...

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

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731 views

1 answer

database - How to connect in java as SYS to Oracle?

I receive this error: java.sql.SQLException: ORA-28009: connection as SYS should be as SYSDBA or SYSOPER How to fix? (I need to be SYS). 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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1.1k views

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database - Postgresql Docker role does not exist

I downloaded the docker container for postgres: https://hub.docker.com/r/library/postgres/, and did the following: $ ... it seems it to me... See Question&Answers more detail:os...

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

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743 views

1 answer

database design - varchar Fields - Is a Power of Two More Efficient?

Is it more efficient to use a varchar field sized as a power of two vs. another number? I'm thinking no, ... any real benefit over varchar(50)? See Question&Answers more detail:os...

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

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624 views

1 answer

database - MySQL pid ended (cannot start mysql)

I have a clean install of MySQL (mysql-5.5.24-osx10.6-x86_64). I am on Lion (OS 10.7.4) with a Mac ... the upgrade, I had to do nothing extra. See Question&Answers more detail:os...

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

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926 views

1 answer

database - Find SQLite Column Names in Empty Table

For kicks I'm writing a "schema documentation" tool that generates a description of the tables and relationships in a ... been able to find 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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649 views

1 answer

database - Exporting from SQLite to SQL Server

Is there a tool to migrate an SQLite database to SQL Server (both the structure and data)? See Question&Answers more detail:os...

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

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665 views

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database - What column type should be used to store serialized data in a mysql db?

What column type should be used to store serialized data in a mysql db? I know you can use varbinary, blob, ... if you have an answer. 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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789 views

1 answer

database - Inner join with 3 tables in mysql

I want to select data from more tables with Inner join. These are my tables. Student (studentId, firstName, ... .gradeId ORDER BY exam.date See Question&Answers more detail:os...

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

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656 views

1 answer

database - Join two sql queries

I have two SQL queries, where the first one is: select Activity, SUM(Amount) as "Total Amount 2009" from Activities ... " (from the 2nd query). See Question&Answers more detail:os...

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

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847 views

1 answer

database - What are the differences between a superkey and a candidate key?

What are the differences between a super key and a candidate key? I have already referred to wiki,dotnet ... explain it with proper example? See Question&Answers more detail:os...

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

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