Azure SQL数据仓库-奇怪的DateTime转换错误/行为

Question

I am reading data from data lake (csv) and when running the below query, I am getting a 'Conversion failed when converting date and/or time from character string' error message.

    select convert(datetime, NullIf(ltrim(rtrim([Date started])), ''), 111)
    FROM dl.temp

Looked through the data and checked the source file as well, couldn't spot anything unusual.

As soon as I include the * and change the query to the below everything runs fine and the conversion seem to be doing its job.

    select convert(datetime, NullIf(ltrim(rtrim([Date started])), ''), 111),*
    from dl.temp

Out of curiosity also wanted to check the max and minimum date, so running max gives me the following:

However when I search for that particular value like below, I don't get any rows returned. It seems like it setting it to the column name. Does anyone know what is going on?

    select *
    from dl.temp
    where [Date started] = 'Date started'

I am running this against an Azure Data Warehouse.

Answer 1

I think you'll find the issue is in your external file format.

In the CREATE EXTERNAL FILE FORMAT you probably need to add FIRST_ROW=2 in your FORMAT OPTIONS.

https://docs.microsoft.com/en-us/sql/t-sql/statements/create-external-file-format-transact-sql