Handling datetime types

[ayush3797]

Why make this change?

Currently, we are incorrectly handling the datetime datatypes. A snippet from BaseSqlQueryStructure class:

As evident from the highlighted portion, even for DateTime .NET type, we are parsing it with DateTimeOffset which is wrong. Just for an example, if you execute a GET request on the stocks_price table which has (categoryid,pieceid,instant) as PK, you would not get any result back even when the record exists for that PK in the table. Why? Because even though instant is a datetime column, it gets parsed as datetimeoffset column. This is shown in the next 2 images.

Also, the existing tests (like the ones fixed in MsSqlGraphQLPaginationTests and GraphQLSupportedTypesTestsBase) were wrongly written, in which values in the range of datetime2 were supplied for datetime column.

What is this change?

1. Correctly return value using DateTime field of the DateTimeOffset parsed value in BaseSqlQueryStructure class,

2. Populate the DbType of the datetime parameters when they are sent to the database so that the database knows the exact type of the parameter. Eg. by default, if you send a datetime2 param without a DbType, it is assumed to be a datetime and an exception is thrown incorrectly by the database. This is done using the map TypeHelper._timeSqlDbTypeToDbType.
   It should be noted 4 sql server types - date, smalldatetime, datetime, datetime2 map to the same .NET system type System.DateTime. The existing TypeHelper._systemTypeToDbTypeMap would not be of any use to us because it has mapping from system type to DbType and all the above 3 sql server types have the same system type. So, we need to rely on the actual mapping from sql server type to DbType which is:
   datetime -> DbType.DateTime, smalldatetime -> DbType.DateTime, datetime2 -> DbType.DateTime2
date -> DbType.Date

3. Fix the existing tests.

How was this tested?

• Integration Tests - Added test for getting single record by PK having a datetime column as a PK column to FindApiTestBase.
• Unit Tests - Added filter/orderby and insert tests to GraphQLSupportedTypesTestsBase.QueryTypeColumnFilterAndOrderByDateTime and GraphQLSupportedTypesTestsBase.InsertIntoTypeColumnfor datetime types - datetime2, smalldatetime, date.

Sample Request(s)

• Example REST request to demonstrate modifications

• Example GQL request to demonstrate modifications

[ayush3797]

/azp run

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[ayush3797]

/azp run

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[ayush3797]

/azp run

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[aaronburtle]

Looks good just a few nits before merging if possible.

[ayush3797]

/azp run

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Azure Pipelines successfully started running 6 pipeline(s).

[seantleonard]

@microsoft-github-policy-service rerun

Comments addressed.

[ayush3797]

Ignoring the failing test for DwSql FindByDateTimePKTest(). @rohkhann will take a look. Not a blocker.