Shulou(Shulou.com)05/31 Report--

Today, I will talk to you about what the simple query statement in SQL refers to. Many people may not know much about it. In order to make you understand better, the editor has summarized the following content for you. I hope you can get something according to this article.

The simplest query in SQL is to find some meta-ancestors (tuple) that meet the criteria from a relationship. This query is similar to selection in relational algebra, and this simple query, like almost all SQL queries, uses three keywords with SQL features: SELECT,FROM and WHERE.

Suppose we want to look up all the films produced by Disney Productions in 1990. In SQL, we say:

SELECT*FROM Movie

WHERE studioName='Disney'AND year=1990

This query shows the select-from-where format unique to most SQL queries.

Where the FROM clause gives the relationship involved in the query.

The WHERE clause gives the conditions for the query.

The SELECT clause states which attributes of meta-ancestors that meet the criteria will be part of the answer.

After reading the above, do you have any further understanding of what the simple query statement in SQL refers to? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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