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Using EXECUTE with a Character String
Use the string concatenation operator (+) to create large strings for dynamic execution. Each string expression can be a mixture of Unicode and non-Unicode data types.

Although each [N] 'tsql_string' or @string_variable must be less than 8,000 bytes, the concatenation is performed logically in the SQL Server parser and never materializes in memory. For example, this statement never produces the expected 16,000 concatenated character string:

EXEC('name_of_8000_char_string' + 'another_name_of_8000_char_string')

Statement(s) inside the EXECUTE statement are not compiled until the EXECUTE statement is executed.

Changes in database context last only until the end of the EXECUTE statement. For example, after the EXEC in this example, the database context is master:

USE master EXEC ("USE pubs") SELECT * FROM authors