MySQL Trigger Code to enter statement based on another value - mysql

Question

EDIT **********
I couldn't get the below code to work so I have tried to run it in the diagram tool on Workbench. This is my code
CREATE DEFINER = CURRENT_USER TRIGGER `MeasureUp_Data`.`bmd_results_BEFORE_INSERT` BEFORE INSERT ON `bmd_l_arm` FOR EACH ROW
BEGIN
INSERT INTO bmd_results VALUES ( new.bmd_l_arm_typ
CASE new.l_arm_tscore
WHEN < -2.5 THEN 'osteoporosis'
WHEN > -2.4 < -1.0 THEN 'osteopenia'
WHEN > -1.0 THEN 'normal'
ELSE NULL
END);
END
Im getting red crosses all though the code. Basically the values will be automatically entered into data.bmd_l_arm and I want the field in data.bmd_results labelled bmd_l_arm_typ to have the text entry based on the numerical result pushed into l_arm_tscore
Thanks for you ongoing help!
I am very new to the coding game and have been creating a Db on MySQL to add some value to my company. I have created the DB schema and want to have a field in one of my table insert a value based on a entry which comes into another table. Basically this is for a medical reporting database and I would like the diagnosis to appear in text on in as a field entry.
This is the table which I would like the values to appear, more specially i would like the column (for example) bmd_sp_typ to inset a VARCHAR (I will specify the result) based on a numerical result in a different table.
CREATE TABLE IF NOT EXISTS `MeasureUp_Data`.`bmd_results` (
`access_no` INT NOT NULL,
`bmd_sp_typ` VARCHAR(45) NULL,
PRIMARY KEY (`access_no`),
INDEX `pat_id_FK_idx` (`pat_id` ASC),
INDEX `fk_site_bmd_site_idx` (`site_id` ASC),
UNIQUE INDEX `pat_id_UNIQUE` (`pat_id` ASC),
UNIQUE INDEX `site_id_UNIQUE` (`site_id` ASC),
UNIQUE INDEX `access_no_UNIQUE` (`access_no` ASC),
CONSTRAINT `fk_demo_results_id`
FOREIGN KEY (`pat_id`)
REFERENCES `MeasureUp_Data`.`patient_demo` (`pat_id`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_site_bmd_site`
FOREIGN KEY (`site_id`)
REFERENCES `MeasureUp_Data`.`site_cont` (`site_id`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB
The table where the numerical result will be found is below. Basically is the value for spine_total_bmd is X then Y will be inserted into bmd_sp_type, alternatively, if spine_total_bmd is A then B will be inserted.
CREATE TABLE IF NOT EXISTS `MeasureUp_Data`.`bmd_spine` (
`access_no` INT NOT NULL,
`spine_total_bmd` INT NULL,
`spine_total_tscore` INT NULL,
`spine_total_zscore` INT NULL,
`spine_total_peakref` INT NULL,
`spine_total_agemat` INT NULL,
PRIMARY KEY (`access_no`),
CONSTRAINT `fk_bmd_spine_access`
FOREIGN KEY (`access_no`)
REFERENCES `MeasureUp_Data`.`bmd_results` (`access_no`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB
Any help for this coding noob will be greatly appreciated.

Answer 1

You can write an INSERT trigger -
CREATE TRIGGER trigger
BEFORE INSERT
ON bmd_spine
FOR EACH ROW
BEGIN
INSERT INTO bmd_results VALUES (
new.access_no,
CASE new.spine_total_bmd
WHEN 1 THEN 'y'
WHEN 2 THEN 'b'
ELSE NULL
END);
END
Also, you can just select data from the table and change values on the fly, and do not store duplicated values. Here it is an example -
SELECT
access_no,
CASE spine_total_bmd
WHEN 1 THEN 'y'
WHEN 2 THEN 'b'
ELSE NULL
END
FROM
bmd_spine;