A query is simply a request for information. Query in programming; It's pretty much the same thing, except that the information is retrieved from a database.
This is very useful for data manipulation – especially for adding, deleting and modifying data. However, no random 'request' is written. You write your query over some predefined code so the database understands the instruction. This code is called query language.
The standard for database management is Structured Query Language (SQL). Remember, SQL is different from MySQL: the first is a query language, and the second is the software that uses that language.
While it is true that SQL is the most popular choice among database software, SQL is not the only query language. There are many other query languages such as AQL, Datalog and DMX.
Regardless, these languages make database communication pretty easy.
How Query Works
Gives meaning to code in any query language. Be it SQL or any other language, both user and database can always exchange information – as long as they 'speak' the same language.
Making a query isn't the only way to request data. In fact, there are many database software options that allow you to use other methods. The most popular of them are:
- Using existing parameters; By default the software has parameter lists in its menu. Users can choose one and then the system will guide you to get the result you want. This process is easy but inflexible and offers limited operations.
- Query by example; The system will show you a set of codes with blank fields that you can fill in and specify the fields and values of your data.
- Query language; This is exactly what we've been talking about so far. Whenever you want to manipulate data, you have to rewrite the queries from scratch. This method requires understanding the query language your database software uses. Even if it's messy, you have full control over your data.
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