I'm trying to make a join to a date table on a column called 'date'.
The issue I have is that the column name is the same as the table and it seems to be making a referencing to the table rather than the column (hence the yellow highlighting). I've found a workaround which is to rename the table - though does anyone know how to explicitly reference the column in the join rather than the table if they have the same name?
You can give aliases to the table/column and use that instead. Otherwise, you can use the table name before the column with a . as a separator, i.e., TableName.date = date.
Related
I have a table that has just a code for the individual column name like "A1G", "Z8H" etc.
This table is a really huge table. Therefore it would not help to manually add the alias name in the SELECT Statement like.
The description for each column code is stored in a different table:
Now I would like to SELECT * from the first table but with the right column header name.
This is stored in the second table within the filters Schema = 'ABC' and Table = 'A'.
That would be desired output:
How would you do that in SQL?
How can I change the column name?
You would be better off just creating a view with all the columns aliased to your preferred names. Once that's done you can select from the view and get the data back with the headings you want.
Look into Inner Join
Or Left Join.
I have I table consisting of 3 columns: system, module and block. Table is filled in a procedure which accepts system, module and block and then it checks if the trio is in the table:
select count(*) into any_rows_found from logs_table llt
where system=llt.system and module=llt.module and block=llt.block;
If the table already has a row containing those three values, then don't write them into the table and if it doesn't have them, write them in. The problem is, if the table has values 'system=a module=b block=c' and I query for values 'does the table have system=a module=d block=e' it returns yes, or, to be precise, any_rows_found=1. Value 1 is only not presented when I send a trio that doesn't have one of it's values in the table, for example: 'system=g module=h and block=i'. What is the problem in my query?
Problem is in this:
where system = llt.system
Both systems are the same, it is as if you put where 1 = 1, so Oracle is kind of confused (thanks to you).
What to do? Rename procedure's parameters to e.g. par_system so that query becomes
where llt.system = par_system
Another option (worse, in my opinion) is to precede parameter's name with the procedure name. If procedure's name was e.g. p_test, then you'd have
where llt.system = p_test.system
From the documentation:
If a SQL statement references a name that belongs to both a column and either a local variable or formal parameter, then the column name takes precedence.
So when you do
where system=llt.system
that is interpreted as
where llt.system=llt.system
which is always true (unless it's null). It is common to prefix parameters and local variables (e.g. with p_ or l_) to avoid confusion.
So as #Littlefoot said, either change the procedure definition to make the parameter names different to the column names, or qualify the parameter names with the procedure name - which some people prefer but I find more cumbersome, and it's easier to forget and accidentally use the wrong reference.
Root cause is alias used for table name.
where system=llt.system and module=llt.module and block=llt.block;
Table name alias in select query and input to procedure having the same name(i.e. llt
). You should consider either renaming one of them.
I keep getting a syntax error in PSQL and I can't figure out why. Any help would be greatly appreciated
SELECT page_code, developer
FROM page
WHERE data_approved=null and approved_by=null
ALTER TABLE page
RENAME COLUM page_code TO unapproved;
You are, probably, looking for alias, not for altering table:
SELECT page_code AS unapproved,
developer
FROM page
WHERE data_approved IS null
AND approved_by IS null
Note, that page table will stay intact while its page_code field will be represented in this particular query as unapproved. Please, be very careful with altering tables since doing this you change the rules for all the users.
Another issue is = null which returns null (neither true nor false). IS null is the right syntax.
ALTER TABLE table_name RENAME new_table_name;
this command will help you to change table name
Rename is used to change the table name and
change is used to rename column name
In SQL insert, generally we specify the names of the columns in the SQL. Is there a way to generate that dynamically? basically if we specify the names of columns then tomorrow if a new col is added, there is a code change involved. How can i avoid this?
I am thinking of follg solution -
How about getting the names of the columns via
select column_name,* from information_schema.columns where table_name = '' order by ordinal_position;
& then create the INSERT statement with the columns? This way we do not specify the column names in the SQL...
Any thoughts?
You can only leave out the column names if you fill all values, but that would also break if a new column is added.
If you specify the names, you can add new columns as much as you want. They will automatically be assigned their default value if you leave your query as it is.
If you don't want them to have the default value, you need to edit the code anyway. Sure, you can dynamically generate the SQL and assign a default value, but that is what your RDBMS does anyway! I don't see your problem.
You can use a default value for the new column.
Assuming you're saying that you'll be getting the column values as input from somewhere else, then you could keep the column names in a config file like a properties file. Then if you're willing to assume that the ordering will always match up, just match up the input values to the column names from the file, and adding a column just means getting a new value to match the new column.
I solved this by getting the names of the columns via
select column_name,* from information_schema.columns where table_name = '' order by ordinal_position;
& then create the INSERT statement with the columns. By this I avoided specifying the column names in the query
I'm trying to create a sql query, but there is this error:
Ambiguous column name 'description'.
Its because this column occurs in both tables.
if I remove the description from the query, it works.
I tried to rename the description-field "AS description_pointer", but the error still occurs.
SELECT TOP 1000 [activityid]
,[activitytypecodename]
,[subject]
,[regardingobjectid]
,[contactid]
,[new_crmid]
,[description] AS description_pointer
FROM [crmtestext_MSCRM].[dbo].[FilteredActivityPointer] as I
Left JOIN [crmtestext_MSCRM].[dbo].[FilteredContact]
ON I.[regardingobjectid] = [crmtestext_MSCRM].[dbo].[FilteredContact].[contactid]
WHERE new_crmid not like '%Null%' AND activitytypecodename like '%E-mail%'
Both tables coming into play in the query have a column named description. You RDBMS cannot guess which column table you actually want.
You need to prefix the column name with the table name (or table alias) to disambiguate it.
Bottom line, it is a good practice to always prefix column names with table names or aliases as soon as several tables come into play in a query. This avoids the issue that you are seeing here and make the queries easier to understand for the poor souls that have no knowledge of the underlying schema.
Here is an updated version of your query with table aliases and column prefixes. Obviously you need to review each column to put the correct alias:
SELECT TOP 1000
i.[activityid]
,i.[activitytypecodename]
,i.[subject]
,c.[regardingobjectid]
,c.[contactid]
,c.[new_crmid]
,c.[description] AS description_pointer
FROM [crmtestext_MSCRM].[dbo].[FilteredActivityPointer] as i
Left JOIN [crmtestext_MSCRM].[dbo].[FilteredContact] as c
ON i.[regardingobjectid] = c.[contactid]
WHERE i.new_crmid not like '%Null%' AND i.activitytypecodename like '%E-mail%'