WHERE only returns rows that match a condition

The WHERE keyword lets you filter the rows returned from your query to only those where the specified condition is true. For example, get only rows where the year column has the value 2022 like SELECT "title", "author" FROM "longlist" WHERE "year" = 2022;.

There’s a bunch of operators you can use in the condition

• = for equal, like WHERE "year" = 2022 year is 2022
• != (or <>) for not equal, like WHERE "year" != 2022 year is anything but 2022.
• You could achieve the same with WHERE NOT "year" = 2022
• LIKE does fuzzy string matching, for example WHERE "title" like 'The%' - % matches any string of characters, _ matches a single character. This finds only titles that start with words that start with The. LIKE is case-insensitive in some DBMSs, but case-sensitive in PostgreSQL - use ILIKE for case-insensitive comparison.
• Range operators <, >, <= and >= when the data in your column can be compared like that (numbers, dates etc). There’s also BETWEEN ... AND ... for inclusive range.

You can combine conditions using logical operators.

• OR like WHERE "year" = 2022 or "year" = 2023
• AND like WHERE "year" = 2022 AND "format" = 'paperback'
• show precedence using (), like WHERE ("year" = 2022 OR "year" = 2023) AND "format" = 'paperback'
• IS and IS NOT are used with NULL , like WHERE "translator" IS NULL to find books with no translator.

Use HAVING instead of WHERE to specify a condition on the result of a GROUP BY rather than a single row.