I have an issue later in my process when I want the append tables with a different Datatypes.
I am creating a new table out of an existing table. One column is the Calenderweek(KW) which was originally a STRING. In order to append my tables later on I need the same datatype for the column.
Is there a way to change the datatype for a column while creating the new table?
CREATE TABLE IF NOT EXISTS
MyNewTable
AS(
SELECT
Column_1 AS
Column_1_alias,
**KW_ AS KW,**
FROM
SourceTable);
What this Query does is that it only grabs the value of the column KW that contains a number, then checks if the STRING value contains a character and removes it from the STRING. Finally it CAST to the desired value type of the column, so it ends as an INT.
CREATE TABLE IF NOT EXISTS
dataset.MyNewTable
AS(
SELECT
Column1 AS
Column1_alias,
CAST(REGEXP_REPLACE(KW,'[^0-9^]','') as INT64) as KW_Alias
FROM
`project.dataset.source`
WHERE REGEXP_CONTAINS(KW,'[0-9]')
);
Another possible solution is to use the function REPLACE instead of REGEXP_REPLACE, to replace the string to a number.
Related
I created a new column [LastLoginDate-NoTime] with the data type Date. I already have another column [LastLoginDate] that is of Datetime datatype.
Columns with the values
I am trying to copy values from the LastLoginDate column to the LastLoginDate-NoTime column using this query:
UPDATE [dbo].[SapUsersExt]
SET [LastLoginDate] = [LastLoginDate-NoTime]
But the problem I am having is that when I execute this query, it sets the data to null in the original column.
Screenshot: Error
I am also trying to convert the data from the LastLoginDate to just date format in the new column LastLoginDate-NoTime so that I can use it in my application. How would I do that?
I am trying to copy values from the LastLoginDate column to the LastLoginDate-NoTime column using this query
In that case, you're doing it exactly backwards - you should use this SQL instead:
UPDATE [dbo].[SapUsersExt]
SET [LastLoginDate-NoTime] = [LastLoginDate]
The first column - right after the SET - is the target column into which your values will be written.
The second column, after the = symbol, is where the data comes from (column or expression).
You had it backwards - setting the column with the actual values, to all NULL ....
This of course only works for a "one time" update - this will not keep your columns in sync over time, when new data is being inserted. For such a case, you'd need a computed column
ALTER TABLE dbo.SapUsersExt
ADD LastLoginDateOnly AS CAST(LastLoginDate AS DATE) PERSISTED;
or a trigger.
Or maybe, you don't even really need to actually store that date-only value - just use
SELECT
CAST(LastLoginDate AS DATE),
.......
if you need to date-only value from LastLoginDate
i got a table with three columns whose type is BYTES
i succeed to make a SELECT SAFE_CONVERT_BYTES_TO_STRING
but now, i wish i could REPLACE my BYTES values by their corresponding STRING in my original table
Replacing the value would imply changing the column type, which is not supported.
My recommendation would be to save your query results to a different destination table then drop the current table and copy the destination table to rename it as the original one.
Is there a way to duplicate a column from a current database table (copy all the column contents from table to a temporary table), Then
Convert the string value in the column and increment it by 1, then
Put all those values in a form of a string back into it's original table?
So pseudocode would look like:
copy column1 from tblReal into tmpcolumn in tblTemp (set tmpcolumn1 as nvarchar(265))
update tblTemp
set tmpcolumn1 = 'TESTDATA' + 1
copy tbmpcolumn1 from tblTemp into column1 in tblReal
So actually you want to change a string column, which holds actually a number, by incrementing its value by 1. Why would you need three steps for that? Just do an update statement on the column immediatly. I don't see why you need intermediate tables.
UPDATE tblReal SET column1 = column1 + 1
Piece of cake. You can use the cast function to transform the varchar to a number and back again in the update statement.
I am working in SQL Server 2008. I have a table with many columns that will not have values (at least, for the given situation). So, they will have a NULL value when I query each of them. I would like to instead make these NULL values be empty strings (i.e., ''). What is the best way to achieve this? My current idea is to set a DEFAULT value of '' on each them at the time that the table is created. However, since there are so many of them, this will be very tedious.
You have 2 options:
As you said, give it a default value of empty string for columns you don't want to be null when you create table/add new columns.
When you select nullable columns from the table you can use IsNull(ColumnName,'') which means if ColumnName is null it'll return empty string ('').
Create a table with the same structure as your current table, with a different name, and the default value as ''.
Insert into that table from your original table.
Delete the original table.
Change the name of the new table to the original table name.
I want to make filtration on a column after selecting a specific value of another column in the same table, I tried to use #... special character followed by the column's name to get the address of this value.
My SQL statement is like the following :
SELECT ATTRIBUTE FROM TABLE WHERE FIELD = '#FIELDNAME';
If I used a specific value instead of #FIELDNAME, it will work properly but it will be static but I need it to be dynamic based on the selected value.
Create another table which will have the list of values that are in the FIELDNAME and give each record a unique id ,then retrieve the value depending on what you have selected by the name of the new table's field preceded by '#...'
I don't know if that what are you looking for, please let me know.
If no triggers are allowed, do you have any date/time column in the table? Is it possible to have that extra column anyway to see the time of a newly inserted row?
You may have to check the lastest row entered, save its field value into a variable. Then do the select based on the variable value.
Based on the vague last row id you could try the following (it's not pretty). But again, if you have date/time that's more accurate.
select attribute from table
where field = (select field from table
where rowid =(select max(rowid) from table))
;
upate
Do you have the priviledge to set up your insert command as below:
insert into table (id, col1, col2,...) values (1,'something', 'something',...)
returning id into variable; -- you may either save field or id depending on your table
Then you may use this variable to select the records you want.