SQL TOPICS

SQL TOPICS

SQL SELECT

Basic syntax: SELECT and FROM

SELECT indicates which columns you'd like to view, and FROM identifies the table that they live in.

If you want to select every column in a table, you can use * instead of the column names:

Rename columns name by using  AS  see this

SQL LIMIT

Automatic LIMIT in Mode

As you might expect, the limit restricts how many rows the SQL query returns. The default value is 100; when this box is checked, it's telling the database to only return the first 100 rows of the query. Because the dataset tutorial.us_housing_units has more than 100 rows, the queries thus far haven't been returning the full result sets. Try turning the LIMIT off (by clicking the check mark next to it) and running this query.

Using the SQL LIMIT command

The limiting functionality is built into Mode to prevent you from accidentally returning millions of rows without meaning to (we've all done it). However, if you're ever using SQL outside of Mode, you can manually add a limit with a SQL command. The following syntax does the same thing as having the box checked with a value of 100:

SELECT *
  FROM tutorial.us_housing_units
 LIMIT 100

SQL WHERE