I have two tables each in different DB on the same server ...with multiple columns in SQL.
I need to fetch the records where the value of one of the column I use is present in TableA and not in TableB. This column is alphanumeric (BIGINT) in TableA while it is different in TableB it is ShortDescription(varchar(100))
TableB column's value is ONLY numbers same as Table A column but without characters (for example 123) while TableA column value can contain for example "ab123"
Now if value "abc123" in TableA is present in Table A and value "123" is not in Table B, then I should get that record from table A. If 123 is present in Table B for that column, then I shouldn't fetch.
How to do?
You need PATINDEX to find the numbers from TableA.Column1 and then match it with TableB.Column2. Below is the query for you:
Select Column1 FROM TableA WHERE EXISTS (SELECT 1 FROM TableB WHERE SUBSTRING(CAST(Column1 AS VARCHAR), PATINDEX('%[0-9]%', CAST(Column1 AS VARCHAR)), LEN(Column1))=Column2)
I am assuming you do not have a common column between two tables. Otherwise you can use the common column to join and put the PATINDEX statement in WHERE clause.
Try this query. It makes things simple by joining the two tables, then utilizing the WHERE clause. I'll just call the common column between the two tables "Id" for the join:
SELECT * FROM TableA
LEFT JOIN TableB ON TableA.Id = TableB.Id
WHERE TableA.Column1 = "ab123" AND TableB.ShortDescription != "123";
Related
Suppose Table A and Table B have various fields. What is an easy way to get the common fields among Table A and Table B ? I want to do an inner join on these tables but I don't know what the common fields are.
Note that this is in PL/SQL. When I table A. or B. I get the list of fields names of each table in a drop down menu. But I would like to get the common fields.
It depends on what do you mean by "common fields".
If you want to get all colums which names are the same in both tables, then you can use this query:
SELECT t1.column_name
FROM user_tab_columns t1
JOIN user_tab_columns t2
ON t1.COLUMN_NAME = t2.COLUMN_NAME
/*
AND t1.DATA_TYPE = t2.DATA_TYPE
AND t1.DATA_LENGTH = t2.DATA_LENGTH
*/
WHERE t1.table_name = 'A'
AND t2.table_name = 'B'
;
Demo: http://sqlfiddle.com/#!4/2b662/1
But if you look at tables in the above demo, you will see that table A has a column named X with datatype VARCHAR2, and table B has also a column named X but of different type INT.
If you want to get all columns that have the same names, the same datatypes and the same length, then uncomment respective conditions in the above query.
Do mean something like this:
TableA has 2 columns: Id and Name.
TableB has 2 columns: Name and PhoneNumber
Query:
SELECT A.Id, A.Name, B.PhoneNumber
FROM TableA A, TableB B
WHERE A.Name = B.Name;
Edit:
If you want know what Columns names there a re from your table I believe you can use DESC TableA. Then you get a list a column names. You can use those to compaire against another list, for example from TableB.
Let's say I write the query
SELECT * FROM table1 JOIN table2 ON table1.ID = table2.student.Number
There are the same values in column "ID" of table1 and in column "Number" of table2.
How will the column with the joined values be named in the result table?
"ID" or "Number"?
Both of them. JOIN does not remove common columns - indeed, if you're doing a join on two tables which share a column name, the result will have two columns with that name. (You can disambiguate them using the table name, e.g. SELECT table1.id FROM table1 JOIN table2 ON (table1.x = table2.y).)
Is it possible to include table name in the returned column if I use wildcard to select all columns from tables?
To explain it further. Suppose I want to join two tables and both tables have the column name “name” and many other columns. I want to use wildcard to select all columns and not explicitly specifying each column name in the select.
Select *
From
TableA a,
TableB b
Where
a.id = b.id
Instead of seeing two column with same name "name", could I write a sql to return one column name as "a.name" (or TableA.name) and one as "b.name"(or TableB.name) without explicitly putting the column name in select?
I would prefer a solution for mssql but other database could be a reference too.
Thanks!
You can use select a.*, ' ', b.* from T1 a, T2 b to make it more visible where columns from T1 end and columns from T2 begin.
You are basically joining two tables on the ID field, so you will only see one column labeled "ID", not two, because you are asking to see only those records where the ID is the same in table a and table b: they share the same id.
Try ...
SELECT 'TableA' AS 'Table', A.* FROM TableA A
WHERE A.id IN (SELECT id FROM TableB)
UNION
SELECT 'TableB' AS 'Table', B.* FROM TableB B
WHERE B.id IN (SELECT id FROM TableA)
ORDER BY id, [Table]
Here is my obstacle.
I have two tables. Table A contains more rows than Table B. I have to merge the results and if Table A does not contain a row from Table B then I insert it into the new set. If however, a row from Table A contains a row with the same primary key as Table B, the new set will take the row from Table B.
Would this best be done in a cursor or is there an easier way to do this? I ask because there are 20 million rows and while I am new to sql, i've heard cursors are expensive.
Your phrasing is a little vague. It seems that you want everything from TableB and then rows from TableA that have no matching primary key in B. The following query solves this problem:
select *
from tableB union all
select *
from tableA
where tableA.pk not in (select pk from tableB)
Yep, cursors are expensive.
There's a MERGE command in later versions of SQL that will do this in one shot, but it's sooo cumbersome. Better to do it in two pieces - first:
UPDATE A SET
field1 = B.field1
,field2 = B.field2
, etc
FROM A JOIN B on B.id = A.id
Then:
INSERT A SELECT * FROM B --enumerate fields if different
WHERE B.id not in (select id FROM A)
An OUTER JOIN should do what you need and be more efficient than a cursor.
Try this query
--first get the rows that match between TableA and TableB
INSERT INTO [new set]
SELECT TableB.* --or columns of your choice
FROM TableA LEFT JOIN TableB ON [matching key criteria]
WHERE TableB.[joining column/PK] IS NOT NULL
--then get the rows from TableA that don't have a match
INSERT INTO [new set]
SELECT TableA.* --you didn't say what was inserted if there was no matching row
FROM TableA LEFT JOIN TableB ON [matching key criteria]
WHERE TableB.[joining column/PK] IS NULL
I want to accomplish something of the following:
Select DISTINCT(tableA.column) INTO tableB.column FROM tableA
The goal would be to select a distinct data set and then insert that data into a specific column of a new table.
SELECT column INTO tableB FROM tableA
SELECT INTO will create a table as it inserts new records into it. If that is not what you want (if tableB already exists), then you will need to do something like this:
INSERT INTO tableB (
column
)
SELECT DISTINCT
column
FROM tableA
Remember that if tableb has more columns that just the one, you will need to list the columns you will be inserted into (like I have done in my example).
You're pretty much there.
SELECT DISTINCT column INTO tableB FROM tableA
It's going to insert into whatever column(s) are specified in the select list, so you would need to alias your select values if you need to insert into columns of tableB that aren't in tableA.
SELECT INTO
Try the following...
INSERT INTO tableB (column)
Select DISTINCT(tableA.column)
FROM tableA
The goal would be to select a distinct data set and then insert that data into a specific column of a new table.
I don't know what the schema of tableB is... if table B already exists and there is no unique constraint on the column you can do as any of the others suggest here....
INSERT INTO tableB (column)Select DISTINCT(tableA.column)FROM tableA
but if you have a unique constraint on table B and it already exists you'll have to exclude those values already in table B...
INSERT INTO tableB (column)
Select DISTINCT(tableA.column)
FROM tableA
WHERE tableA.column NOT IN (SELECT /* NOTE */ tableB.column FROM tableB)
-- NOTE: Remember if there is a unique constraint you don't need the more
-- costly form of a "SELECT DISTICT" in this subquery against tableB
-- This could be done in a number of different ways - this is just
-- one version. Best version will depend on size of data in each table,
-- indexes available, etc. Always prototype different ways and measure perf.