The Order of Basic SQL execution
09 Aug 2021 | SQL dataSQL, short for Structured Query Lanuguage, is widely used in proramming and desigined for managing data in a relational database management system.
A very basic SQL query looks like this:
select *
from
[table_name]
where [col_name] = *
and
...
In the modern world, SQL query planners can do all sorts of tricks to make queries run more efficiently, but they must always reach the same final answer as a query that is executed per the standard SQL order of execution. This order is:
| Order | Clause | Function |
|---|---|---|
| 1 | from | Choose and join tables to get base data |
| 2 | where | Filters the base data |
| 3 | group by | Aggregates the base data |
| 4 | having | Filters the aggregated data |
| 5 | select | Returns the final data |
| 6 | order by | Sorts the final data |
| 7 | limit | Limits the returned data to a raw count |
Looks like different from the writing order right?
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