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add column to mysql table if it does not exist
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Note that INFORMATION_SCHEMA isn't supported in MySQL prior to 5.0. Nor are stored procedures supported prior to 5.0, so if you need to support MySQL 4.1, this solution isn't good.
One solution used by frameworks that use database migrations is to record in your database a...
Copy values from one column to another in the same table
...e name and it's surrounded by grave accent (aka back-ticks `) as this is MySQL convention to escape keywords (and TABLE is a keyword in that case).
BEWARE, that this is pretty dangerous query which will wipe everything in column test in every row of your table replacing it by the number (regardless...
Rank function in MySQL
...nd out rank of customers. Here I am adding the corresponding ANSI standard SQL query for my requirement. Please help me to convert it to MySQL .
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Is there a way to pass the DB user password into the command line tool mysqladmin?
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Just found out the answer....
mysqladmin processlist -u root -pYOURPASSWORDHERE
No space between your password and the -p
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Is Redis just a cache?
...ures are fundamentals of programs, or applications. Consider you are using SQL databases as storage technology and need to construct a list, a hash map, a ranking set or things like that, it's kind of pain in the neck. Redis can provide you these functionalities directly in a very simple way, thus h...
Questions every good Java/Java EE Developer should be able to answer? [closed]
...y there are two Date classes; one in java.util package and another in java.sql?
What happens if an exception is thrown in finally block? Is the remaining finally executed or not?
There is a garbage collector alright, but then is memory leak totally absent in a Java applications? If not, how so?
Fo...
What is Express.js?
...aries such as Mongoose for MongoDB, Sequelize (http://sequelizejs.com) for SQL databases, Waterline (https://github.com/balderdashy/waterline) for many databases into the stack.
Alternatives
Other Node.js frameworks to consider (https://www.quora.com/Node-js/Which-Node-js-framework-is-best-for...
MongoDB relationships: embed or reference?
...y you much) there is no immediate need to normalize data like you would in SQL. In particular any data that is not useful apart from its parent document should be part of the same document.
Separate data that can be referred to from multiple places into its own collection.
This is not so much a "s...
How to find the size of an array in postgresql
...w that the array is 1-dimensional (which is likely) and are running PostgreSQL 9.4 or higher, you can use cardinality:
SELECT cardinality(id) FROM example;
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How to test Spring Data repositories?
...serting object instances through the EntityManager or repo, or via a plain SQL file) and then execute the query methods to verify the outcome of them.
Testing custom implementations
Custom implementation parts of the repository are written in a way that they don't have to know about Spring Data JP...