I have Table called WORKERS, and the Table consists of totalNumberOfWorkers, i want to set the maximum value of the worker to be 30 and it shouldn't exceed over 30, it should be in the range of 0 to 30.
I have tried this, but it doesn't work and shows an error, my code isn't right.
ALTER TABLE WORKERS
CONSTRAINT WORKERS_CHECK CHECK (totalNumberOfWorkers => 0 AND totalNumberOfWorkers <31);
Here is the Table Called WORKERS
+------------------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------------------+-------------+------+-----+---------+-------+
| WorkerID | int(6) | NO | PRI | NULL | |
| dateOfWork | date | NO | | NULL | |
| timeOfWork | time | NO | | NULL | |
| descOfWorker | varchar(50) | NO | | NULL | |
| totalNumberOfWorkers | int(2) | NO | | NULL | |
+------------------------+-------------+------+-----+---------+-------+
Found a solution
ALTER TABLE WORKERS
ADD CONSTRAINT TOTALNUMBER_CHECK1 CHECK(totalNumberOfWorkers BETWEEN 1 AND 30);
Related
I not sure if this is related to Laravel or not but I created the table with Laravel. I've got a table called programmers
DESC programmers;
+--------------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------+---------------------+------+-----+---------+----------------+
| id | bigint(20) unsigned | NO | PRI | NULL | auto_increment |
| name | varchar(255) | NO | | NULL | |
| age | int(11) | NO | | NULL | |
| created_at | timestamp | YES | | NULL | |
| updated_at | timestamp | YES | | NULL | |
| framework_id | int(10) unsigned | NO | | NULL | |
| test | tinyint(1) | NO | | NULL | |
+--------------+---------------------+------+-----+---------+----------------+
as you can see there's a column called test that's not nullable and has a default value of null. When I to run the following command from the database I expected an error
INSERT INTO programmers (name, age, framework_id) VALUES ('Melly2', 19, 2)
it actually worked fine and here's the data
SELECT * FROM programmers;
+----+--------+-----+---------------------+---------------------+--------------+------+
| id | name | age | created_at | updated_at | framework_id | test |
+----+--------+-----+---------------------+---------------------+--------------+------+
| 1 | melly | 20 | 2022-05-03 16:36:12 | 2022-05-03 16:36:12 | 1 | 0 |
| 2 | Melly2 | 19 | NULL | NULL | 2 | 0 |
+----+--------+-----+---------------------+---------------------+--------------+------+
the test column actually defaulted to 0 not null, and if I were to run the following command it tells me I can't have null as a value as expected
INSERT INTO programmers (name, age, framework_id, test) VALUES ('Melly2', 19, 3, null);
ERROR 1048 (23000): Column 'test' cannot be null
question: can someone briefly explain why test column didn't default to null?
In this scenario, the default value is null only if you don't provide a value. But when you provide some value, it should be compatible with the datatype you set for the column.
Here the datatype is tinyint. So, you should provide the values from true/false which infact will be converted into 1/0; else you should insert integers example:0,1,2,... etc.
I have a webapp that I'm building. This webapp will take as input some products (cars, motos, boats, houses, etc...) and each product will have one or more photos associated with it. The id of each of photo is generated by the uniqid() function of php.
My problem is:I can't seem to fit more than two id_photos into the same column
+-----------+------------------------------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+------------------------------------------+------+-----+---------+----------------+
| carid | int(11) | NO | MUL | NULL | auto_increment |
| brand | enum('Alfa Romeo','Aston Martin','Audi') | NO | | NULL | |
| color | varchar(20) | NO | | NULL | |
| type | enum('gasoline','diesel','eletric') | YES | | NULL | |
| price | mediumint(8) unsigned | YES | | NULL | |
| mileage | mediumint(8) unsigned | YES | | NULL | |
| model | text | YES | | NULL | |
| year | year(4) | YES | | NULL | |
| id_photos | varchar(30) | YES | | NULL | |
+-----------+------------------------------------------+------+-----+---------+----------------+
What I would like to happen is something like this: INSERT INTO cars(id_photos) values ('id_1st_photo', 'id_2nd_photo')
Ending up having something like this:
| 60 | Audi | Yellow | diesel | 252352 | 1234112 | R8 | 1990 | id_1st_photo id_2nd_photo |
Eventually I would have to grab those photos from the folders they are in which is something like this: /var/www/website/$login/photos/id_of_photo with the query select id_photos from cars where carid=$id.
You may found some data types that is not proprelly good for the data that the server will receive but I'm one week into mysql and I'll worry about data types later on.
First of all I don't know if that is possible, if it's not how can I design something to work like that?
I have found this question that is quite the same of mine but I can't seem to implement something like this: add multiple values in one column
You can insert the concatenated values into a field. But it is not a good practice. You can create another table with foreign key having the id of the parent table.
You can easily adapt the approach in the linked question and even remove one table needed:
You first table stays almost the same, but has the id_photos column removed:
+-----------+------------------------------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+------------------------------------------+------+-----+---------+----------------+
| carid | int(11) | NO | MUL | NULL | auto_increment |
| brand | enum('Alfa Romeo','Aston Martin','Audi') | NO | | NULL | |
| color | varchar(20) | NO | | NULL | |
| type | enum('gasoline','diesel','eletric') | YES | | NULL | |
| price | mediumint(8) unsigned | YES | | NULL | |
| mileage | mediumint(8) unsigned | YES | | NULL | |
| model | text | YES | | NULL | |
| year | year(4) | YES | | NULL | |
+-----------+------------------------------------------+------+-----+---------+----------------+
Then you'll add a second table to store the links to the photo ids:
+-----------+------------------------------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+------------------------------------------+------+-----+---------+----------------+
| carid | int(11) | NO | MUL | NULL | |
| id_photos | varchar(30) | NO | | NULL | |
+-----------+------------------------------------------+------+-----+---------+----------------+
Both tables are linked by the field carid (You should even make carid in the second table a foreign key pointing to the one in the first table).
Each id_photos then results in a new row in the second table.
To query the data you probably need a JOIN between both tables and maybe a GROUP BY to reduce the result to one row per carid again, but this depends on the other usecases.
You can insert the string formatted woth multiple photo name
INSERT INTO cars(id_photos) values ('id_1st_photo, id_2nd_photo')
In this way you don'have a well normalized database structure so you have problem when retrive the singole foto name ..
i suggest you of normalize the id_photo column in a separata table with reference to the master table and in this way store each single photo in one row
I am posting this thread in order to have some advices regarding the performance of my SQL query.
I have actually 2 tables, one which called HGVS_SNP with about 44657169 rows and another on run table which has an average of 2000 rows.
When I try to update field Comment of my run table it takes lot's of time to perform the query. I was wondering if there is any method to increase my SQL query.
Structure of HGVS_SNP Table:
+-----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| snp_id | int(11) | YES | MUL | NULL | |
| hgvs_name | text | YES | | NULL | |
| source | varchar(8) | NO | | NULL | |
| upd_time | varchar(32) | NO | | NULL | |
+-----------+-------------+------+-----+---------+-------+
My run table has the following structure:
+----------------------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------------------+--------------+------+-----+---------+-------+
| ID | varchar(7) | YES | | NULL | |
| Reference | varchar(7) | YES | MUL | NULL | |
| HGVSvar2 | varchar(120) | YES | MUL | NULL | |
| Comment | varchar(120) | YES | | NULL | |
| Compute | varchar(20) | YES | | NULL | |
+----------------------+--------------+------+-----+---------+-------+
Here's my query:
UPDATE run
INNER JOIN SNP_HGVS
ON run.HGVSvar2=SNP_HGVS.hgvs_name
SET run.Comment=concat('rs',SNP_HGVS.snp_id) WHERE run.Compute not like 'tron'
I`m guessing since you JOIN a text column with a VARCHAR(120) column that you don`t really need a text column. Make it a VARCHAR so you can index it
ALTER TABLE `HGVS_SNP` modify hgvs_name VARCHAR(120);
ALTER TABLE `HGVS_SNP` ADD KEY idx_hgvs_name (hgvs_name);
This will take a while on large tables
Now your JOIN should be much faster,also add an index on compute column
ALTER TABLE `run` ADD KEY idx_compute (compute);
And the LIKE is unnecessary,change it to
WHERE run.Compute != 'tron'
I have two tables gains and final_gains.
I'm wondering how I could calculate the sum of two columns and insert it into a different table...I need to be using a WHERE clause which would be inside runescape_name inside the gains table.
Like so
hitpoints_end_exp - hitpoints_starting_exp,
magic_end_exp - magic_starting_exp,
range_end_exp - range_starting_exp
And insert the result into final_gains.hp_gained, final_gains.magic_gains and final_gains.range_gained
Here are my two tables
gains
+------------------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------------------+-------------+------+-----+---------+-------+
| runescape_name | varchar(12) | NO | PRI | NULL | |
| hitpoints_starting_exp | int(50) | NO | | NULL | |
| magic_starting_exp | int(50) | NO | | NULL | |
| range_starting_exp | int(50) | NO | | NULL | |
| hitpoints_end_exp | int(50) | NO | | NULL | |
| magic_end_exp | int(50) | NO | | NULL | |
| range_end_exp | int(50) | NO | | NULL | |
+------------------------+-------------+------+-----+---------+-------+
final_gains
+----------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------------+-------------+------+-----+---------+-------+
| runescape_name | varchar(12) | NO | PRI | NULL | |
| hp_gained | int(50) | NO | | NULL | |
| magic_gained | int(50) | NO | | NULL | |
| range_gained | int(50) | NO | | NULL | |
+----------------+-------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
Sorry If I'm unclear, trying to explain the best as I can, I hope I'm clear enough
Use an INSERT, SELECT like this:
INSERT INTO final_gains (runescape_name, hp_gained, magic_gains, range_gained)
SELECT runescape_name,
hitpoints_end_exp - hitpoints_starting_exp,
magic_end_exp - magic_starting_exp,
range_end_exp - range_starting_exp
FROM gains;
In order to avoid duplicate keys:
INSERT INTO final_gains (runescape_name, hp_gained, magic_gains, range_gained)
SELECT runescape_name,
hitpoints_end_exp - hitpoints_starting_exp,
magic_end_exp - magic_starting_exp,
range_end_exp - range_starting_exp
FROM gains
ON DUPLICATE KEY
UPDATE hp_gained = hitpoints_end_exp - hitpoints_starting_exp,
magic_gains = magic_end_exp - magic_starting_exp,
range_gained = range_end_exp - range_starting_exp;
This is untested code, but should be close.
Note: I removed the first suggestion as it s not applicable to these table definitions. runescape_name is primary key in table final_gains so it has to be inserted/assigned as well.
In my app, I allow people to create additional rooms for inventory purposes. Let's say I have a table called "user_data." The d_key field is the data type for a lack of a better description. I have that just in case I introduce more custom fields for the user. Anyways, I want every user to have a room that's called None. This way any item that doesn't have a room assigned to it will default to "None."
What's the best way to introduce None into the table? Users won't be able to delete this default room, but they can edit/delete rooms they input into the DB table.
user_data table
+---------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| user_id | int(11) | NO | | NULL | |
| d_key | varchar(20) | NO | | NULL | |
| d_value | varchar(40) | NO | | NULL | |
+---------+-------------+------+-----+---------+----------------+
Sample data:
+----+---------+----------+--------------+
| id | user_id | d_key | d_value |
+----+---------+----------+--------------+
| 20 | 2 | location | bedroom |
| 21 | 2 | location | living room |
| 22 | 2 | location | attic |
| 23 | 3 | location | kitchen |
+----+---------+----------+--------------+
Add the row as part of your user creation process.
For existing users, loop over the users and ensure they have a "none" room; if they don't, insert one.