I wish to all know how the tables in my database are related to each other (i.e PK/FK/UK) and hence i created a database diagram of all my tables in SQL Server. The diagram that was created was not easily readable and had to scroll (horizontally and sometimes vertically) to see the table on the other end.
In short SQL's db diagram are not UI friendly when it comes to knowing relationships between many tables.
My (simple) Question: Is there something like database diagram which can do what db diagram did but in "good" way?
A relationship works by matching data in key columns, usually columns (or fields) that have the same name in both tables. In most cases, the relationship connects the primary key, or the unique identifier column for each row, from one table to a field in another table.
Example of one-to-many relation in SQL Server Create two tables (table 1 and table 2) with their own primary keys. Add a foreign key on a column in table 1 based on the primary key of table 2. This will mean that table 1 can have one or more records related to a single record in table 2.
There are three types of relationships between the data you are likely to encounter at this stage in the design: one-to-one, one-to-many, and many-to-many. To be able to identify these relationships, you need to examine the data and have an understanding of what business rules apply to the data and tables.
Sometimes, a textual representation might also help; with this query on the system catalog views, you can get a list of all FK relationships and how the link two tables (and what columns they operate on).
SELECT
fk.name 'FK Name',
tp.name 'Parent table',
cp.name, cp.column_id,
tr.name 'Refrenced table',
cr.name, cr.column_id
FROM
sys.foreign_keys fk
INNER JOIN
sys.tables tp ON fk.parent_object_id = tp.object_id
INNER JOIN
sys.tables tr ON fk.referenced_object_id = tr.object_id
INNER JOIN
sys.foreign_key_columns fkc ON fkc.constraint_object_id = fk.object_id
INNER JOIN
sys.columns cp ON fkc.parent_column_id = cp.column_id AND fkc.parent_object_id = cp.object_id
INNER JOIN
sys.columns cr ON fkc.referenced_column_id = cr.column_id AND fkc.referenced_object_id = cr.object_id
ORDER BY
tp.name, cp.column_id
Dump this into Excel, and you can slice and dice - based on the parent table, the referenced table or anything else.
I find visual guides helpful - but sometimes, textual documentation is just as good (or even better) - just my 2 cents.....
Just another way to retrieve the same data using INFORMATION_SCHEMA
The information schema views included in SQL Server comply with the ISO standard definition for the INFORMATION_SCHEMA.
sqlauthority way
SELECT
K_Table = FK.TABLE_NAME,
FK_Column = CU.COLUMN_NAME,
PK_Table = PK.TABLE_NAME,
PK_Column = PT.COLUMN_NAME,
Constraint_Name = C.CONSTRAINT_NAME
FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS C
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS FK ON C.CONSTRAINT_NAME = FK.CONSTRAINT_NAME
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS PK ON C.UNIQUE_CONSTRAINT_NAME = PK.CONSTRAINT_NAME
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU ON C.CONSTRAINT_NAME = CU.CONSTRAINT_NAME
INNER JOIN (
SELECT i1.TABLE_NAME, i2.COLUMN_NAME
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS i1
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE i2 ON i1.CONSTRAINT_NAME = i2.CONSTRAINT_NAME
WHERE i1.CONSTRAINT_TYPE = 'PRIMARY KEY'
) PT ON PT.TABLE_NAME = PK.TABLE_NAME
---- optional:
ORDER BY
1,2,3,4
WHERE PK.TABLE_NAME='something'WHERE FK.TABLE_NAME='something'
WHERE PK.TABLE_NAME IN ('one_thing', 'another')
WHERE FK.TABLE_NAME IN ('one_thing', 'another')
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