ASKER
SQL (Structured Query Language) is designed to be used in conjunction with relational database products as of a means of working with sets of data. SQL consists of data definition, data manipulation, and procedural elements. Its scope includes data insert, query, update and delete, schema creation and modification, and data access control.
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To locate the "bad data, look at the ISNUMERIC function:
https://docs.microsoft.com/en-us/sql/t-sql/functions/isnumeric-transact-sql?view=sql-server-2017
You didn't provide the nvarchar column or which table it is in so something like:
select some_column from some_table where ISNUMERIC(some_column) <> 1;