Dynamically create a table from the values of grid view. (C#)

Create a table in your database that has the desired schema. It doesn't have to contain any data. (Allowing NULL values will accommodate months that don't have 31 days.)

CREATE TABLE SCHEMA_TEMPLATE
(
    NAME nvarchar(255) NULL,
    Day1 DATE NULL,
    ...
    Day31 DATE NULL
) ON PRIMARY;

Then, write a stored proc that will create the desired data table that has the same schema as the SCHEMA_TEMPLTE table. Pass the desired table name to it (for instance, "May2018"):

CREATE PROCEDURE dbo.sp_CreateTableForMonth
    @tableName nvarchar(50)
AS
BEGIN
    -- this query will duplicate the schema of the SCHEMA_TEMPLATE table.
    DECLARE @query nvarchar(MAX) =
    'SELECT TOP 0 * INTO '+@tableName+' FROM dbo.SCHEMA_TEMPLATE';
    EXEC sp_executesql @query;
END

After that, it's a simple matter to put your data into the table from your code.

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I would revisit your schema as well. Seems to me there might be a better way to represent the data, such as just putting all the data into the same table, and using a MERGE command to update the table. This beats having one table for every month...