I found the similar question and solution for the SQL server. I want to replace all my null values with zero or empty strings. I can not use the update statement because my table has 255 columns and using the update for all columns will consume lots of time.
Can anyone suggest to me, how to update all the null values from all columns at once in PostgreSQL?
If you want to replace the data on the fly while selecting the rows you need:
SELECT COALESCE(maybe_null_column, 0)
If you want the change to be saved on the table you need to use an UPDATE. If you have a lot of rows you can use a tool like pg-batch
You can also create a new table and then swap the old one and the new one:
# Create new table with updated values
CREATE TABLE new_table AS
SELECT COALESCE(maybe_null_column, 0), COALESCE(maybe_null_column2, '')
FROM my_table;
# Swap table
ALTER TABLE my_table RENAME TO obsolete_table;
ALTER TABLE new_table RENAME TO my_table;
I have a table that I'm trying to append unique values to. Every month I get list of user logins to import into this table. I would like to keep all the original values and just append the new and unique values onto the existing table. Both the table and the flatfile have a single column, with unique values, built like this:
_____
login
abcde001
abcde002
...
_____
I'm bulk ingesting the flat file into a temp table, with this:
IF OBJECT_ID('tempdb..#FLAT_FILE_TBL') IS NOT NULL
DROP TABLE #FLAT_FILE_TBL
CREATE TABLE #FLAT_FILE_TBL
(
ntlogin2 nvarchar(15)
)
BULK INSERT #FLAT_FILE_TBL
FROM 'C:\ImportFiles\logins_Dec2021.csv'
WITH (FIELDTERMINATOR = ' ');
Is there a join that would give me the table with existing values + new unique values appended? I'd rather not hard code a loop to evaluate it line by line.
Something like (pseudocode):
append unique {login} from temp_tbl into original_tbl
Hopefully it's an easy answer for someone out there.
Thanks!
Poster on Reddit r/sql provided this answer, which I'm pursuing:
Merge statement?
It looks like using a merge statement will do exactly what I want. Thanks for those who already posted replies.
You can check if a record exists using 'EXISTS' clause and insert if it doesn't exist in the target table. You can also use MERGE statement to achieve the same. Depending on what you want to do to the existing records in the target table, you can modify the Merge statement. Here since you only want to insert new records, you need to specify only what you want to do when a new record comes in. Here is an example
MERGE original_tbl T
USING temp_tbl S
ON T.login = S.login
WHEN NOT MATCHED THEN
INSERT (login)
VALUES(S.login)
Another solution would be to left join the target table to the temp table and insert only when the record doesn't exist.
INSERT INTO original_tbl(login)
SELECT S.Login
FROM temp_tbl S
LEFT JOIN original_tbl T
ON S.Login = T.Login
WHERE T.Login IS NULL
I am trying to insert values into 1 column of a table when a condition is satisfied.
Note: The table already contains data for all the columns but for 1 which is empty. I would like to insert value into this 1 column depending on the WHERE clause.
I have this query:
INSERT INTO <TABLE_NAME>
(COLUMN_NAME)
(VALUE)
WHERE <CONDITION>
I am getting an exception:
Incorrect Syntax Near WHERE Keyword
I am able to do this using UPDATE:
UPDATE <TABLE_NAME>
SET <COL_NAME>
WHERE <CONDITION>
But was wondering why the INSERT query was failing. Any advise appreciated.
As I understand your problem, you already have data in one row, and one column in that row does not have value, so you want to add value in to that column.
This the scenario for Update existing row, not the insert new row. You have to use UPDATE clause when data already present and you want to modify record(s). Choose insert when You want to insert new row in table.
So in your current scenario, Update Clause is your friend with Where Clause as you want to modify subset of records not all.
UPDATE <TABLE_NAME>
SET <COL_NAME>
WHERE <CONDITION>
INSERT Clause does not have any Where Clause as per any RDBMS syntax(I think). Insert is condition less sql query, While SELECT, UPDATE, DELETE all are conditional commands, you can add Where Clause in all later ones.
In order to add a value into the one column when the rows are already populated, you will need to use the update statement.
If you need to insert a new row that has a where clause, you will need to use an insert into select statement:
INSERT INTO <table> (<columns>)
SELECT <columns>
FROM <table>
WHERE <condition>;
The SQL Insert dont accept where parameters, you could check this: SQL Insert Definition...
I do not know the whole question of what you want to do, but just using the INSERT statement is not possible, however it is possible to condition the insertion of data into a table, if this data is dependent on another table or comes from another table ... check here... SQL Insert explain in wikipedia
like this:
Copying rows from other tables
INSERT INTO phone_book2
SELECT *
FROM phone_book
WHERE name IN ('John Doe', 'Peter Doe')
or
INSERT INTO phone_book2 ( [name], [phoneNumber] )
SELECT [name], [phoneNumber]
FROM phone_book
WHERE name IN ('John Doe', 'Peter Doe')
Based on your question I have the feeling that you are trying to UPDATE a column in a table rather than insert.
Something like:
UPDATE column SET value WHERE different_column_value = some_value
I know this is kinda late, for those who still want to use the where clause in an insert query, it's kinda possible with a hack.
My understanding is that, you want to insert only if a condition is true. Let's assume you have a column in your database "surname" and you want to insert only if a surname doesn't exist from the table.
You kinda want something like INSERT INTO table_name blha blha blah WHERE surname!="this_surname".
The solution is to make that cell unique from your admin panel.
Insert statement will insert a new record. You cannot apply a where clause to the record that you are inserting.
The where clause can be used to update the row that you want.
update SET = where .
But insert will not have a where clause.
Hope this answers your question
INSERT syntax cannot have WHERE clause. The only time you will find INSERT has WHERE clause is when you are using INSERT INTO...SELECT statement.
I take it the code you included is simply a template to show how you structured your query. See the SO questions here, here and the MSDN question here.
In SQL Server (which uses Transact-SQL aka T-SQL) you need an UPDATE query for INSERT where columns already have values - by using the answer #HaveNoDisplayName gave :)
If you are executing INSERT / UPDATE from code (or if you need it regularly) I would strongly recommend using a stored procedure with parameters.
You could extend the procedure further by adding an INSERT block to the procedure using an IF-ELSE to determine whether to execute INSERT new record or UPDATE an existing, as seen in this SO answer.
Finally, take a look at SQLFiddle for a sandbox playground to test your SQL without risk to your RDMS :-)
Private case I found useful: Conditional insert which avoids duplications:
-- create a temporary table with desired values
SELECT 'Peter' FirstName, 'Pan' LastName
INTO #tmp
-- insert only if row doesn't exist
INSERT INTO Persons (FirstName, LastName)
SELECT *
FROM #tmp t
WHERE NOT EXISTS (SELECT * FROM Persons where FirstName=t.FirstName and LastName=t.LastName)
If the data need to be added for a column for an existing row then it’s UPDATE.
INSERT is creating a new row in the table.
For conditional INSERT, you can use the MERGE command.
I've never created a trigger before and I'm trying to read online but am a little confused.
I want to create a trigger on a table that on insert, it will grab some data from different columns and insert it into a few different other tables.
I'm not sure how to write the T-SQL to get the data from the columns..
insert into [othetTable]
values ([col1 from row that was inserted], [col5 from row that was inserted])
What would the syntax be to get those values?
thanks
Use the inserted virtual table that is available to triggers. Note that there could be multiple rows in this table - your trigger could be processing multiple inserts at once.
Therefore, you need to use something like the following syntax:
insert into othertable
select col1, col5
from inserted
This will insert a row into othertable for each inserted row.
I am trying to add an additional column and value to an existing insert query - both integers, and running into trouble.
Anything to look out for?
you don't give much to go in in your question:
I am trying to add an additional
column and value to an existing insert
query - both integers, and running
into trouble.
Anything to look out for?
it is best practice to list all columns you intend to include values for in the list of columns, so make sure you add them there, as well as the VALUES list:
insert into YourTable (col1, col2,..., newCol1, newCol2)
VALUES (1,2,...,new1, new2)
make sure the you get the column names spelled correct and that the table actually has those new columns in it.
make sure the column name sequence is the same as your insert data sequence.
Example
INSERT INTO TABLENAME
(ColumnName1,ColumnName2) VALUES (1,'data')
Becomes
INSERT INTO TABLENAME
(ColumnName1,ColumnName2,ColumnNameNEW) VALUES (1,'data','newcolumndata')
Notice both the new column name and the new data are in the third position in the sequence.