I have a database named blog and a table named users. While creating this table, I want to make the data type of the id column int. In another table, I want to make the data type of the date column datetime, but if I choose either of these data type, the data type is reset when I press the apply button. May you help me ?
I cannot select these columns because the data type appears empty when creating a foreign key.
Related
I have a PostgresSQL table that has a Date column of type TEXT
Values look like this: 2019-07-19 00:00
I want to either cast this column to type DATE so I can query based on latest values, etc.... or create a new column of type DATE and cast into there (so I have both for the future). I would appreciate any advice on both options!
Hope this isn't a dupe, but I havn't found any answers on SO.
Some context, I will need to add more data later on to the table that only has the TEXT column, which is why i want to keep the original but open to suggestions.
You can alter the column type with the simple command:
alter table my_table alter my_col type date using my_col::date
This seems to be the best solution as maintaining duplicate columns of different types is a potential source of future trouble.
Note that all values in the column have to be null or be recognizable by Postgres as a date, otherwise the conversion will fail.
Test it in db<>fiddle.
However, if you insist on creating a new column, use the update command:
alter table my_table add my_date_col date;
update my_table
set my_date_col = my_col::date;
Db<>fiddle.
I have a table TableWithLongerName which has connection foreign key to TableWithLongName. With Go-Pg I want to retrieve data of TableWithLongerName with data from TableWithLongName embedded to it. But unfortunately TableWithLongName has column VeryLongColumnName.
When I run query.Relation("TableWithLongName") it returns error
can't find column table_with_long_name__very_long_c in Model TableWithLongerName
I have create alias for domain in TableWithLongName but it gets overwritten.
I have a CSV which contains numbers stored as strings example: 1,200 when loading in these are stored as VARCHAR
I'd like to store these as integers. So tested the below;
update data
set stringy_number = replace (stringy_number,',','')::integer
This runs and removes the , from the number but doesn't change the character type. I then tried;
update data
set stringy_number::integer = replace (stringy_number,',','')::integer
Which threw a syntax error. At which point I switched to the below which worked, but I don't understand why I can't set a data type along with an update
alter table data
alter column stringy_number type integer using replace(stringy_number,',','')::integer;
update works on the values. You can cast from a datatype to another, but the result is still cast to to underlying column type.
--> you can save a "number" in a text column because it is easy to cast a number to a text. You cannot save a letter in a numerical column because the cast cannot (easily) be done.
alter column works on the entire column type. When changing the type, you can supply a custom transformation method allowing the old data to match the new data type.
Since Firebird 3, I can't modify a column type.
Before I use this kind of update:
update RDB$RELATION_FIELDS set
RDB$FIELD_SOURCE = 'MYTEXT'
where (RDB$FIELD_NAME = 'JXML') and
(RDB$RELATION_NAME = 'XMLTABLE')
because I get ISC error 335545030 ("UPDATE operation is not allowed for system table RDB$RELATION_FIELDS").
Maybe there is another way in Firebird 3?
Firebird 3 no longer allows direct updates to the system tables, as that was a way to potentially corrupt a database. See also System Tables are Now Read-only in the release notes. You will need to use DDL statements to do the modification.
It looks like you want to change the data type of a column to a domain. You will need to use alter table ... alter column ... for that. Specifically you will need to do:
alter table XMLTABLE
alter column JXML type MYTEXT;
This does come with some restrictions:
Changing the Data Type of a Column: the TYPE Keyword
The keyword TYPE changes the data type of an existing column to
another, allowable type. A type change that might result in data loss
will be disallowed. As an example, the number of characters in the new
type for a CHAR or VARCHAR column cannot be smaller than the existing
specification for it.
If the column was declared as an array, no change to its type or its
number of dimensions is permitted.
The data type of a column that is involved in a foreign key, primary
key or unique constraint cannot be changed at all.
This statement has been available since before Firebird 1 (InterBase 6.0).
Firebird 2.5 manual, chapter Data Definition (DDL) Statement, section TABLE:
ALTER TABLE tabname ALTER COLUMN colname TYPE typename
I just create a new view as follows
CREATE OR REPLACE VIEW gettreelistvw AS
SELECT "CRM".groupid, 'pointrewarding'::text AS applicationid, "CM".menuid, "CM".menuname, "CM".levelstructure, "CM".moduleid, "CM".haschild, "CM".installed
FROM core_capabilitymap "CRM"
JOIN core_menus "CM" ON "CRM".menuid::text = "CM".menuid::text;
ALTER TABLE gettreelistvw
when i execute this error appear
ERROR: cannot change data type of view column "applicationid" from
unknown to text
although I already cast the value of applicationid column to text. it's still recognized as unkown datatype
'pointrewarding'::text
The alternative method of postgres conversion also didn't work.
CAST('pointrewarding' AS TEXT)
How to solve this problem.
If you want to change the data type of a view's columns, you have to drop it, then create it.
Version 9.2 docs
CREATE OR REPLACE VIEW .... The new query must generate the same columns that were generated by the existing view query (that is, the same column names in the same order and with the same data types), but it may add additional columns to the end of the list.
Emphasis added.