![]() ![]() this runs no problem but is inefficient. test what happens if adding constrint to primary key columnĬREATE UNIQUE INDEX CONCURRENTLY u_test_pkey ON unique_test (pkey) SQL Error : ERROR: relation "unique_target_1" already exists Which TablePlus build number are you using (the number on the welcome screen, E. Detail: Key (unique_no)=(a) is duplicated. Which driver are you using and version of it (Ex: PostgreSQL 10.0): SQLite 3.27.2 / PostgreSQL 11.x / MySQL 8.x /. ![]() Here is the generic syntax for dropping a constraint: ALTER TABLE tablename DROP CONSTRAINT constname That applies to PostgreSQL, MS SQL Server, Oracle. To drop the constraint, we use DROP CONSTRAINT command. SQL Error : ERROR: could not create unique index "u_test_2" That can be a UNIQUE, PRIMARY KEY, FOREIGN KEY, or CHECK constraint. check what happens when column is not uniqueĬREATE UNIQUE INDEX CONCURRENTLY u_test_2 ON unique_test (unique_no) INSERT INTO unique_test (pkey, unique_yes, unique_no)ĬREATE UNIQUE INDEX CONCURRENTLY u_test_1 ON unique_test (unique_yes) If the column is the primary key, the unique constraint can be added without error but in this case it would be preferable to just recognize that the column must be unique based on the primary key.Ĭode examples of this below. in this case would prefer to just check for the existing constraint. If there is already a constraint of the same name a useful error is returned. The Check constraint can appear pretty much anywhere in the table definition during creation. If the column is not unique adding the constraint will return an error. If the column is unique I can add a constraint. ![]() I'm running the queries using psycopg2 so adding that tag on the off chance there's something in there that can help with this. I'm aware of the UNIQUE constraint, but I'm wondering if there is a better way to do the check. Writing the data to another table as suspect would be allowable since no actual financial transaction would have been allowed.ģ) This data is stored in no other table (this was my initial idea to place it in another table and use a foreign key lookup on the card number + data and reject it if not the same.I am pushing the boss to do this but he has to confer with some one about legality.I need to ensure that the values in a column from a table are unique as part of a larger process. Obviously the script engine adding the data will have to be modified as well, but I should be able to handle that part. Since a new entry would be the entire transaction involving suspect information the entire transaction should be refused. I am as yet unable to find a way to do this with sql, and am new enough to postgresql that the functions and triggers elude me.Įdit: Per ypercube's suggestion I am ading what I should have said in the beginning.ġ) The information is being entered from an employee operated form (web based script of some kind, I will look into this further)Ģ) The table / constraint should refuse to allow the insert if the conditions are detected. (Note: This isn't the full table, but it is enough to demonstrate the issue with, I hope.) Table Plus is a GUI tool that can talk to many different kind of database engines, such as PostgreSQL, MySQL, Mongo, Redis, etc. Since a given card can wind up in the table more than once, but should never do so with different card holder data, multiple entries need to be allowed IF THEY ARE EXACTLY THE SAME! But if a card number appears more than once, with different holder data, it should raise an error. Also, you won't see the constraint listed in informationschema. ![]() In an effort to help us combat fraud, we want to ensure that the combination of data for a given table row is the only way that the card in question is ever entered. PostgreSQL uses unique indexes to implement unique constraints, so the effect is the same, with an important caveat: you can't perform upserts ( ON CONFLICT DO UPDATE) against a unique index like you would against a unique constraint. Sec character(4), - credit card security number from reverseĬard_holder_fname character(20), - first name of card holderĬard_holder_lname character(20), - last name of card holderĬard_holder_mi character(1), - middle initial (if given)Ĭard_type character(1), - Visa, Master Card, or Discover Idx integer NOT NULL DEFAULT nextval('cc_idex_seq'::regclass),Ĭard_num character(16), - credit card number I have the following table: CREATE TABLE cc I have found several questions on this site, and found references in the postgres 9.1 documentation which allude to this issue, but I am new enough to this that my understanding of the various complex examples is insufficient for me to grasp the concept. To say I am a newbie to postgresql would be an insult to the newbies! I have been working on this for only a day or so. ![]()
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