MySQL Understanding a Table

Question

I am new to MySQL and I created a table, but I am not exactly sure what is going on.
I have these lines:

mysql> CREATE TABLE tutorials_tbl(
   -> tutorial_id INT NOT NULL AUTO_INCREMENT,
   -> tutorial_title VARCHAR(100) NOT NULL,
   -> tutorial_author VARCHAR(40) NOT NULL,
   -> submission_date DATE,
   -> PRIMARY KEY ( tutorial_id )
   -> );

Obviously CREATE TABLE tutorials_tbl creates a table named tutorials_tbl, but what is the purpose of the other lines?

Downvoted this one. This could have been easily pulled using google or any other search engine by simply putting in 'mysql create table statement'. No effort shown here... — Kris Gruttemeyer, Jul 09 '14 at 18:06

score 0 · Answer 1 · answered Jul 09 '14 at 17:59

0

The other lines define the columns in the table and a key (index) for looking up rows by unique values in tutorial_id. You should read about CREATE TABLE in the docs.

answered Jul 09 '14 at 17:59

elixenide

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so VARCHAR(100) NOT NULL -- what does this accomplish? – user3771865 Jul 09 '14 at 18:01
That is a column that can hold up to 100 characters (a string, like `foo bar`) and cannot be NULL. The `VARCHAR` column only takes as much storage space as it needs, unlike `CHAR`, which always takes the amount of space specified, even if the contents are shorter. – elixenide Jul 09 '14 at 18:02

score 0 · Answer 2 · answered Jul 09 '14 at 18:00

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The other lines are used for columns which includes their names, their datatypes, their size and some constraints applied to them

answered Jul 09 '14 at 18:00

SparkOn

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score 0 · Answer 3 · edited Jul 09 '14 at 18:20

Well Other lines are the table columns, data types and the constraint

mysql> CREATE TABLE tutorials_tbl(
-> tutorial_id INT NOT NULL AUTO_INCREMENT, ... This line creates a column with an integer data type (that's numbers) which must always have a have a value it at all times(not null) and when you insert data in other columns it automatically insert in the column in a sequence ..1...2...3.
-> tutorial_title VARCHAR(100) NOT NULL,... creates a column with a Variable Character type with maximum length of 100. So you can only store a maximum length of 100 characters inside
-> tutorial_author VARCHAR(40) NOT NULL,.. same as above with max length of 40 and cannot be empty
-> submission_date DATE,.. another colume with a data data type. can only contain a date format content
-> PRIMARY KEY ( tutorial_id ) you enforcing a primary key constraint to make sure that no duplicate values are stored in the tutorial_id
-> );

MySQL Understanding a Table

3 Answers3