02 SQL: Basics_Writing Queries (3)

(source: Codecademy, https://www.codecademy.com)

LIMIT : specify the maximum number of rows the result set will have

CASE : create different outputs (usually in the SELECT statement)

• Each WHEN tests a condition and the following THEN gives us the string if the condition is true
• The ELSE gives us the string if all the above conditions are false
• The CASE statement must end with END

• Rename the whole CASE statement to ‘Mood’ using AS

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Let’s summarize:

• SELECT is the clause we use every time we want to query information from a database.
• AS renames a column or table.
• DISTINCT return unique values.
• WHERE is a popular command that lets you filter the results of the query based on conditions that you specify.
• LIKE and BETWEEN are special operators.
• AND and OR combines multiple conditions.
• ORDER BY sorts the result.
• LIMIT specifies the maximum number of rows that the query will return.
• CASE creates different outputs.

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