"Horse Table" in a MySQL database is not working? - mysql

Question

I want to create a database with a table with the following criteria and constraints:
ID - integer with range 0 to 65 thousand, auto increment, primary key
RegisteredName - variable-length string with max 15 chars, not NULL
Breed - variable-length string with max 20 chars, must be one of the following: Egyptian Arab, Holsteiner, Quarter Horse, Paint, Saddlebred
Height - number with 3 significant digits and 1 decimal place, must be ≥ 10.0 and ≤ 20.0
BirthDate - date, must be ≥ Jan 1, 2015
So far I have wrote this
CREATE TABLE horse (
ID SMALLINT AUTO_INCREMENT PRIMARY KEY,
RegisteredName VARCHAR(15) NOT NULL,
Breed VARCHAR(20), CHECK (Breed="Egyptian Arab" "Holsteiner" "Quarter Horse" "Paint" "Saddlebred")
Height DECIMAL(3,1) CHECK (Height=>10.0) CHECK (Height<=20.0),
BirthDate DATE CHECK (BirthDate=>"Jan 1, 2015")
);
After reading all of the suggestions and input you provided I corrected my code to be as follows.
CREATE TABLE Horse (
ID SMALLINT ***UNSIGNED*** AUTO_INCREMENT PRIMARY KEY,
RegisteredName VARCHAR(15) NOT NULL,
Breed VARCHAR(20) CHECK (Breed="Egyptian Arab" "Holsteiner" "Quarter Horse" "Paint" "Saddlebred")***,***
Height DECIMAL(3,1) CHECK ***(Height between 10.0 AND 20.0)***,
BirthDate DATE CHECK ***(BirthDate >='2015-01-01')***
);
On line 2 I added UNSIGNED, on line 4 I moved the comma, on line 5 I removed an extra check statement, my incorrectly formatted inequalities and rewrote it using between instead. I corrected the 6th line to use the proper date format.
As a result workbench was able to properly execute and added my table to the schema on the left side bar.

Answer 1

You said not to do this for you, so I'll just link you to relevant MySQL documentation and you can read them.
ID SMALLINT AUTO_INCREMENT PRIMARY KEY,
If you want it to be unsigned so it supports values 0 - 65535, you need to use SMALLINT UNSIGNED. See https://dev.mysql.com/doc/refman/8.0/en/numeric-type-syntax.html
A signed SMALLINT can have values from -32768 to 32767. That is, the same total number of values (216), but half of them are negative.
CHECK (Breed="Egyptian Arab" "Holsteiner" "Quarter Horse" "Paint" "Saddlebred"),
If you want to compare to multiple values, use the IN(...) operator.
But I'd recommend using a lookup table instead of baking the list of horse breeds into your table definition. Using a lookup table is more flexible because you can add or remove values more easily, and each breed may need to have other attributes too.
Height DECIMAL(3,1) CHECK (Height=>10.0) CHECK (Height<=20.0),
MySQL supports an inequality operator >= but does not support a synonym operator =>. See documentation for operators: https://dev.mysql.com/doc/refman/8.0/en/comparison-operators.html#operator_greater-than-or-equal
In fact, I don't know any programming language that supports => or =< as inequality operators. They tend to support >= and <=. See https://en.wikipedia.org/wiki/Relational_operator#Standard_relational_operators
But even better for this case, use the BETWEEN operator. That way you don't need two inequality conditions.
BirthDate DATE CHECK (BirthDate=>"Jan 1, 2015")
Another use of => that should be >=.
MySQL doesn't understand that format for dates. You should use dates in YYYY-MM-DD format. See: https://dev.mysql.com/doc/refman/8.0/en/date-and-time-literals.html
Another option is to parse a string in the format you show into a MySQL-compatible date by using the STR_TO_DATE() function, but it's easier to just use the standard MySQL date format.
One more tip: You will thank yourself later if you learn the right types of quotes to use in SQL. See: When to use single quotes, double quotes, and backticks in MySQL

Answer 2

This is what I entered:
CREATE TABLE Horse (
ID SMALLINT UNSIGNED AUTO_INCREMENT,
RegisteredName VARCHAR(15) NOT NULL,
Breed VARCHAR(20) CHECK (Breed="Egyptian Arab" "Holsteiner" "Quarter Horse" "Paint" "Saddlebred"),
Height DECIMAL(3,1) CHECK (HEIGHT BETWEEN '10.1' AND '19.9'),
BirthDate DATE CHECK (birthdate > '2015-01-01'),
PRIMARY KEY (ID)
);