I have created two tables in Snowflake.
create or replace TRANSIENT TABLE TESTPARENT (
COL1 NUMBER(38,0) NOT NULL,
COL2 VARCHAR(16777216) NOT NULL,
COL3 VARCHAR(16777216) NOT NULL,
constraint UNIQ_COL3 unique (COL3)
);
create or replace TRANSIENT TABLE TESTCHILD3 (
COL_A NUMBER(38,0) NOT NULL,
COL_B NUMBER(38,0) NOT NULL,
ABCDEF VARCHAR(16777216) NOT NULL,
constraint FKEY_1 foreign key (COL_A, COL_B) references TEST_DB.PUBLIC.TESTPARENT1(COL1,COL2),
constraint FKEY_2 foreign key (ABCDEF) references TEST_DB.PUBLIC.TESTPARENT(COL3)
);
Now I want to execute a query and see the names of columns that are involved in FKEY_2 FOREIGN KEY
in Table TESTCHILD3, but it seems like there are no DB Table/View that keeps this information. I can find out the column names for UNIQUE KEY & PRIMARY KEY but there is nothing for FOREIGN KEYS.
EDIT
I have already tried INFORMATION_SCHEMA.TABLE_CONSTRAINTS, along with INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS and all the other system tables. No luck. Only DESC TABLE is giving me some info related to CONSTRAINTS and COLUMNS but that also has FOREIGN KEY CONSTRAINTS information missing.
SHOW IMPORTED KEYS IN TABLE <fk_table_name>;
Updated answer:
I was checking on something unrelated and noticed a very efficient way to list all primary and foreign keys:
show exported keys in account; -- Foreign keys
show primary keys in account;
When you limit the call to a table, it appears you have to request the foreign keys that point to the parent table:
show exported keys in table "DB_NAME"."SCHEMA_NAME"."PARENT_TABLE";
You can check the documentation for how to limit the show command to a specific database or schema, but this returns rich information in a table very quickly.
maybe you can try to query this view: INFORMATION_SCHEMA.TABLE_CONSTRAINTS
Note: TABLE_CONSTRAINTS only displays objects for which the current role for the session has been granted access privileges.
For more see: https://docs.snowflake.net/manuals/sql-reference/info-schema/table_constraints.html
Related
Is it possible to save a list of strings into a SQLite column in swift4?
If you're looking for an array data type like you find in some SQL engines, SQLite does not have that. You theoretically could encode this list somehow (e.g. a JSON array), but that's pretty kludgy. So, I'd probably go ahead and normalize that, putting the multiple strings in a separate table.
E.g. Let's say you wanted a table users, that had user_id, name, and an array of privileges. You'd probably instead do something like:
CREATE TABLE users (
user_id INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT NOT NULL
);
CREATE TABLE users_privileges (
user_privilege_id INTEGER PRIMARY KEY AUTOINCREMENT,
user_id INTEGER NOT NULL,
privilege TEXT NOT NULL,
FOREIGN KEY (user_id) REFERENCES users (user_id)
);
I have two tables One named "Root" which has columns Id,RootNumber, in which Id is primary Key.
Now when I tried to create another table with RootNumber as the foreign key I get below error
InnerException {"There are no primary or candidate keys in the
referenced table 'dbo.Root' that match the referencing column list in
the foreign key ("FK_CNTR_Root", \r\nCould not create constraint or
index. See previous errors."} System.Exception
{System.Data.SqlClient.SqlException}
this.CreateTableWithId32("CNTR", "Id", s => s
.WithColumn("CNTRNumber").AsString(10).NotNullable()
.WithColumn("CNTRName").AsString(10).NotNullable()
.WithColumn("RootNum").AsInt32().NotNullable()
.ForeignKey("FK_CNTR_Root", "Root", "RootNumber")
The error is very clear. You can make only the PrimaryKey column to be referenced as ForeignKey in another table. So Either make Id as a foreign key in other table or Change RootNumber to PrimaryKey of Root table.
Refer to this basic Foreign Key definition.
I think I'm pretty close on this one, but can't get it to click.
I've got two simple tables set up.
Table A:
CREATE TABLE customer(
id INTEGER PRIMARY KEY,
first_name TEXT,
last_name TEXT,
email TEXT UNIQUE NOT NULL,
password TEXT NOT NULL,
create_time TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
);
I've got two rows of data populating correctly in Table A.
Table B:
CREATE TABLE address(
...> id INTEGER PRIMARY KEY,
...> street_address_1 TEXT NOT NULL,
...> street_address_2 TEXT,
...> street_address_3 TEXT,
...> city TEXT NOT NULL,
...> state TEXT NOT NULL,
...> zip TEXT NOT NULL);
And I've successfully imported a CSV file into that table.
I'm trying to create a 3rd table that joins Table A to Table B with the use of Foreign Keys.
I can create the table with the code below, but when I try to select the table, I'm getting a blank, which means I'm obviously doing something wrong. I'm expecting to see data where the two tables overlap on mutual Id numbers, i.e. where the ID from customer = Id from address I'd like to see the data from both tables for those rows appear in Table C.
Table C (the join table):
CREATE TABLE customer_address(
id INTEGER PRIMARY KEY,
customer_id INTEGER,
address_id INTEGER,
first_name TEXT NOT NULL,
last_name TEXT NOT NULL,
email TEXT NOT NULL,
password TEXT NOT NULL,
street_address_1 TEXT NOT NULL,
street_address_2 TEXT,
street_address_3 TEXT,
city TEXT NOT NULL,
state TEXT NOT NULL,
zip TEXT NOT NULL,
FOREIGN KEY (customer_id) REFERENCES customer(id),
FOREIGN KEY (address_id) REFERENCES address(id)
);
Thanks!
I imported the data to the address table using this:
sqlite> .mode csv
sqlite> .import address.csv address
I manually typed in data to the first table using this:
insert into customer(first_name, last_name, email, password)
values('Ad','Mac','a.Mac#gmail.com','Mab'),('Brian','Obrien','bob#example.com','123456');
Don't duplicate the data in your join table (often called a bridge table). This should do for Table C:
CREATE TABLE customer_address(
id INTEGER PRIMARY KEY,
customer_id INTEGER,
address_id INTEGER,
FOREIGN KEY (customer_id) REFERENCES customer(id),
FOREIGN KEY (address_id) REFERENCES address(id));
Duplicating columns is bad practice because it 1)defeats the purpose of using a relational model; 2)can lead to conflicting records if information is updated or deleted in one table, but not another.
Furthermore, you shouldn't have street_address_1, street_address_2, street_address_3 all in the same table. That's a violation of First Normal Form. Think of it this way, can a person have more than three addresses? Can they have two addresses in different cities? Do all three of those addresses have the same zip?
Continuing to the post of reading-from-XML-and-storing-the-values-in-database-using-grails
am facing an another problem in it. As the employee id is related to other tables as foreign key how am suppose to insert the data into the database without conflict what i want to add in grails code to avoid the below displayed error.
com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException:Cannot
add or update a child rowL a foreign key constraint fails.. ( CONSTRAINT 'EMPLOYEE_ID_HEADER'
FOREIGN KEY ('EMPLOYEE_ID') REFERENCES 'employee_header'('employee_id'))
here employee_id is a column and employee_header is a separate table that contains employee_id as a foreign key.
Finally I got the answer, when you are inserting the values in database the related foreign key tables will get affects initially. So to handle this situation we have to insert the foreign key related table at first then the table we need to add exactly.
For the reference, at first I had given the code like this
sql.executeInsert("insert into order_item (order_id,product_id,
order_item_seq_id) values (${order_id},${product_id},${order_item_seq_id})")
sql.executeInsert("insert into product(product_id) values(${product_id})")
This first inserts the order_item table then the foreignkey constraint table product, so the data did not inserted. So the correct code is
sql.executeInsert("insert into order_header(order_id) values(${order_id})")
sql.executeInsert("insert into product(product_id) values(${product_id})")
sql.executeInsert("insert into order_item (order_id,product_id,
order_item_seq_id) values (${order_id},${product_id},${order_item_seq_id})")
Now this inserts the data successfully without errors.
I use sqlite(3.7.4) in iphone.
I create a table like:
create table A (UserName varchar (50) primary key, Num integer);
Then I insert the record below twice:
('abc',1);
Normally there should be only one record in DB.
However I found in the DB
(abc,1);
( ,1);
I'm confused that as UserName is primary key and why there are two records!
I don't know what's the problem.
Can anyone help me?
thank you.
Why you want use username as primary key. Primary key should unique identify record. What is why when you inserted twice in second time you have primary key constraint violation
create table A (UserName varchar (50) primary key, Num integer, unique (UserName));