Change numeric column type to another numeric column type:

Cast the "Integer64" column to "Real64":

Take blood sugar measurements on a list of days:

Cast the "date" column to "Date" type:

Take a Tabular object where numeric data has been recorded as strings:

Cast the "val" column to a numeric type:

Change the vector type of a column in a Tabular object:

Cast several columns to the same type simultaneously:

Use CastColumns[tab,typerules] to change the types of the columns of a Tabular object tab:

The same result can be achieved using Tabular[tab,<|"ElementType"typerules|>]:

Or using ToTabular[tab,"Rows",<|"ElementType"typerules|>]:

Take a Tabular object with string columns:

Instead of using CastColumns, a new schema can be constructed with the new column types:

Impose the schema on the Tabular object:

The action of CastColumns can be reproduced using TransformColumns with appropriate functions:

String column keys containing spaces require the use of explicit quotation marks:

Take a Tabular object with a column of real-valued levels of blood sugar:

CastColumns effectively uses the Automatic conversion method for each column:

Such conversion fails in this case because reals cannot always be faithfully projected into integers:

Use TabularColumn with an explicit conversion method that includes rounding of reals when converting to integers:

Use InsertColumns to reinsert the new column: