MySQL error involving backticks - mysql

Question

I'm having some problems with this piece of mySQL code that is not wanting to get fixed
CREATE TABLE `DatabaseMGR`
(
`databaseID` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`primCat` INT UNSIGNED NOT NULL,
`databaseName` VARCHAR(20),
UNIQUE KEY (`databaseID`),
PRIMARY KEY (`databaseID`),
INDEX `databaseID`
)ENGINE = InnoDB;
It says that there is an error at line 1 with the regular "check your mysql syntax for right usage" error in response to ` usage. Is there something I'm missing? I'm new to sql so I might be missing something obvious.
Thanks.

Answer 1

The main point for your problem is at the line you are defining the index. In create table statement, you should use it with this syntax:
create table table_name (
...
index `INDEX_NAME` (`INDEX_COLUMN`)
);
So you can fix your problem by changing your code to below:
CREATE TABLE `DatabaseMGR`
(
`databaseID` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`primCat` INT UNSIGNED NOT NULL,
`databaseName` VARCHAR(20),
UNIQUE KEY (`databaseID`),
PRIMARY KEY (`databaseID`),
INDEX `ix_databaseID` (`databaseID`) # Note the change on this line
)ENGINE = InnoDB;
However, in MySQL primary key column gets an index by default, so you can leave out that line totally, that results in the following code:
CREATE TABLE `DatabaseMGR`
(
`databaseID` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`primCat` INT UNSIGNED NOT NULL,
`databaseName` VARCHAR(20),
UNIQUE KEY (`databaseID`),
PRIMARY KEY (`databaseID`)
)ENGINE = InnoDB;
To improve more:
databaseID is already a primary key, so you do not have to make define it unique again, since: primary key = unique + not null
Since MySQL is case insensitive, you should not use camel case names. So instead of databaseID, better to say database_id. There are more naming convention you can go through, though I will not mention here.
So for final table defination I suggest:
CREATE TABLE `database_mgr`
(
`database_id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`prim_cat` INT UNSIGNED NOT NULL,
`database_name` VARCHAR(20),
PRIMARY KEY (`databaseID`)
)ENGINE = InnoDB;