logo
down
shadow

MySQL about constraint


MySQL about constraint

By : Arsalan
Date : November 28 2020, 11:01 PM
may help you . MySQL ignores check expression.
Manual: Create Table
code :
CREATE TABLE T_CAR (
    CAR_ID INTEGER NOT NULL PRIMARY KEY,
    CAR_MARK CHAR(32) NOT NULL,
    CAR_MODEL VARCHAR(16),
    CAR_NUMBER CHAR(10) NOT NULL,
    CAR_COLOR ENUM('white', 'black', 'red', 'green', 'blue') NOT NULL
)


Share : facebook icon twitter icon
How to drop a composite MySQL constraint and/or one column used in the constraint? (Allowing for limitations described.)

How to drop a composite MySQL constraint and/or one column used in the constraint? (Allowing for limitations described.)


By : user3536294
Date : March 29 2020, 07:55 AM
With these it helps In a MySQL 5.0.45 database, I want to remove a 2-column UNIQUE constraint because it includes a column I am going to drop. One of the columns included in the two-column UNIQUE constraint is also FK-constrained in the same table - however I think that that is irrelevant to what follows. , I believe this should work
code :
-- drop the constraint, index and column
ALTER TABLE book DROP FOREIGN KEY book_library_id_fkey;
DROP INDEX library_id ON book;
ALTER TABLE book DROP COLUMN external_id;
-- Recreate the index and foreign key if necessary
ALTER TABLE book ADD CONSTRAINT book_library_id_fkey FOREIGN KEY(library_id) REFERENCES library(id);
ALTER TABLE books ADD KEY library_id (library_id);
MySQL ADD CONSTRAINT fail with [Err] 1215 - Cannot add foreign key constraint

MySQL ADD CONSTRAINT fail with [Err] 1215 - Cannot add foreign key constraint


By : nittinkaushik
Date : March 29 2020, 07:55 AM
like below fixes the issue You're referring to the foodType table in your foreign key constraint definition. You should create that table before adding a constraint to it.
Moreover, that table should have field id as a primary key, matching the type of foodType_id.
Why are there auto increment gaps in MySQL when violating a unique key constraint, but not a primary key constraint?

Why are there auto increment gaps in MySQL when violating a unique key constraint, but not a primary key constraint?


By : Jorge Alejandro
Date : March 29 2020, 07:55 AM
I wish this helpful for you If the auto increment field is the primary key, then duplication in the primary key can only happen if you explicitly set the auto increment field's value in the insert statement to an already existing value in that field (why you would do this is beyond me).
As mysql documentation on using auto increment says:
arrival date and departure constraint with mysql (check constraint)

arrival date and departure constraint with mysql (check constraint)


By : Stephanie Hock
Date : March 29 2020, 07:55 AM
it helps some times I suggest you to do the checks back-end side in your php code before inserting records in the table and front-end side with js. If the arrival date is > of the departure date you don't have to make a request to your server, so your js must handle this problem. For more security just before execute the query you can add another check.
LARAVEL:MYSQL : Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails

LARAVEL:MYSQL : Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails


By : VJEF
Date : March 29 2020, 07:55 AM
it should still fix some issue Set the user migration to earlier, before the books table migration happens. Otherwise, there is no user table in existence yet to reference when creating the books table, and thus the error.
This one first:
code :
Schema::create('users', function (Blueprint $table) {...}
Related Posts Related Posts :
  • Inserts MySQL when column count doesn't match
  • How to get id of those persons who have matching month and year only in dob column
  • Delete all duplicates in mysql table
  • Group by bucket (with NULL values)
  • Mysql Crostab query
  • Broken Pipe Exception on Grails App
  • Multiple Criteria Update
  • Ignore duplicates on GROUP BY
  • undefined method `gsub' for nil:NilClass or how to use gsub method in rails
  • How to get all possible combinations among rows of the same table
  • DB table design for maintaining dynamic price of a product in MIS
  • Querying related rows based on order and column value
  • Can't decide whether normalization or de-normalization would work
  • Laravel working out with multiple data in a column
  • MYSQL - Order By Id In DESC Order, Group By X
  • MySQL Foreign Key Values
  • mysql union two queries with order by
  • I have three tables. I want to have one table. ReDesign my table
  • mySQL query Randomly takes a long time to execute
  • mysql Sorting by Event Name
  • Sum multiple identical tables in mySQL
  • Mysql single select with dynamic columns using max
  • SQL Enum Error 1064
  • Does MySQL maintain a time complexity of O(logn) when searching for a range of values?
  • SQL : 2 columns in 1 in result set
  • mySQL, select BOTH table_rows AND column_name from information_schema
  • I can't get max from counted value in sql
  • MySQL Interval Issue Extra Results
  • Select with inner join, start and Limit SQL
  • efficient way to match users common data in the database?
  • How to select all values of 'A' that match with several B's (MySQL)
  • A Problem Storing Arabic Chars in Database
  • Cannot create .edmx for MySql Database with mysql.data.entity.EF6 in Visual Studio
  • Single batched query or mapped queries for efficiency?
  • Concurrent mysql queries causing large query queue's
  • How to create two tables with first 75% and remaining 25% of another table in MySQL?
  • How to understand this MySQL query containing a JOIN?
  • MySQL/Rails - Mysql2::Error (Access denied for user 'rails_user'@'localhost' to database 'simple_cms_development'):
  • Atomic counter - redis vs postgres or other?
  • SELECT in WHERE clause that uses outer information
  • Obtaining differences between MySQL tables
  • insert into 2column table, avoiding duplicate records
  • How do I create a stored procedure that accepts a user Id and returns the user’s full name and occupation and 1 email ad
  • Replace subquery with join
  • Can a left join be expressed as a right join and vice versa?
  • Is mysql designed to create and drop databases frequently?
  • MySQL: How do I check which entries for each group has a value greater than the average values in its corresponding grou
  • Ruby MySQL Database Migration Script
  • Complex meta_query and orderby with multiple custom post types, and multiple date column names
  • Update table in SQL, WHERE clause multiple fields
  • How to check a condition whether table exist or not in RMysql
  • MySQL GROUP unless value equals 0
  • MySQL SELECT WHERE only digits, spaces and one slash
  • How to use foreign key in this case?
  • Mysql - use result of another query inside subquery
  • How to write a SQL query that can get below result?
  • Receiving SQLNonTransientConnectionException on Google Appengine
  • getting common joins for every combination of entries from a table
  • MySQL: Add a condition on a subquery from a joint table
  • mysql stored procedure with the if condition gives errors
  • shadow
    Privacy Policy - Terms - Contact Us © soohba.com