Using DML Statements
I’ve been trying to get through this section of the course for a while now, so I’m basically forcing myself to take notes.
DML – Data Manipulation Language
Common DML Statements:
SELECT – retrieves data
INSERT – adds data
UPDATE – modifies data
DELETE – removes data
BULK INSERT – imports a data file
The SELECT statement basically retrieves the data you request.
The most basic one is:
SELECT * FROM tablename;
This one will retrieve all rows and columns (including duplicates) from the table, “tablename.”
If you don’t want duplicate rows, you could use the following instead:
SELECT DISTINCT * from tablename;
I bring up the SELECT DISTINCT because in my work I almost always use SELECT DISTINCT rather than just SELECT, as I only very rarely want duplicates.
To limit the number of rows returned, one thing you can do is add a WHERE clause after the “FROM” clause that winnows down the data a bit more.
I’m only 2 minutes in, but it’s time for my bed. More notes tomorrow. 🙂