how can get data from two tables?

Ashok

8y1.2k

Hi All,

How can get the data from two tables with out having the forigen key constraints?

please help me

Thanks to all

11 Replies

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Shahriar Nikkhah8y ago
try to find a relational field(s) in between both tables, so lets assume the related field is F1
If you are 100% sure that this is the right key just use the right JOIN if not you must study and understand the data, to do that
1 - use a inner join on f1
2- use a right join on f1
3- user a left join on f1

now check the number of orphan records and parent without child, this approch will help you to validate the selected field (f1) in your joins
good luck
0
Piyush Agarwal8y ago
Use Joins...... thats the best way
0
chaithanya k8y ago
Two fetch records from Two tables There are two ways
1.Union and Union All
2.Joins
1.Using Union and Union All needs the same table to have similar schematic structure
2.Using joins the both the table should have atleast one column to be having identical values from both the tables.
+1
Hakan Axheim8y ago
Of course you can use UNION / UNION ALL but I think it's better to use INNER JOIN if you want to fetch data from totally different tables.

An INNER JOIN is used to combine two tables into a new table. A UNION is used to combined rows into a new row. Duplicated rows are elimated when using UNION.

Performance is actually almost the same. For better performance use indexes.
+3
Sumit Chaudhary8y ago
You can not use join and because of there is no forigen key and can Union use same data type should be same like

select City from table1
Union
select City from table2
+4
Hakan Axheim8y ago
You have several options to do that!

The old fashion way is.

SELECT alias1.col1,alias2.col1
FROM table1 as alias1, table2 as alias2
WHERE alias1.col1 = alias2.col2;

The new way to join two tables is:

SELECT table1.col1,table2 col1
FROM table1
INNER JOIN table2 ON (table1.col1 = table2.col1)
+3
Dharmraj Thakur8y ago
Joins are meaningless without having a relationship (Not necessary to create the foreign key). Use joins when any table having a reference to another table.
If a relationship between tables is not there then you can use union or other ways to get mixed data.
+4
Shefali Mishra8y ago
U can use joins or else u can use Union /Union All
+1
Bharathi Raja8y ago
1. SELECT <column list>
2. FROM TABLE1 JOIN TABLE2
3. USING (column name)
+3

Sumit Chaudhary8y ago

Can you please explained table structure and how data you want.?

Piyush Pansuriya8y ago

Hi,

Both table have common column to join the table, no need to primary key or forigen key.

Columns : ID, Name, Address
Columns : ID, Dept, Desig.
SELECT * FROM
INNSER JOIN ON table1.ID = table2.ID