Hello everybody,
The MySQL database I wrote for MySQL Lesson 1 & MySQL Lesson 2 is finally ready for querying (and this series of querying posts). Querying, for those that don’t know, is basically asking the database a question and using SQL to find the answer.
First off, let’s start with the most basic query-SELECT * FROM (table). The asterisk means “everything”, as in “Select everything from a certain table”.
In this case, I wrote SELECT * FROM mydb.Singer, which means I would select every record and every column from the Singer table (remember mydb is the name of the schema).
Let’s try that same query again, except with the album table.
Just as with the previous query, every record and every column are selected from this table.
Now, once again using the album table, here’s a query where only certain columns are selected.
For this query, I selected the columns name, duration, and release date, which means my query will only display every record for these three columns.
- At first my query kept giving me a syntax error message for the Release Date field, so I just put the name of the field in back-ticks; these errors usually happen with fields that have spaces in their names (like Release Date) because MySQL isn’t sure whether the word Date is part of the field name or a separate data type. Back-ticks usually solve this issue.
As you can see, I selected the Singer Name, Age, and Gender columns from the Singer table; thus, only the records for those three columns will be displayed.
Thanks for reading,
Michael