Both NEWID() and NEWSEQUENTIALID() give globally unique values of type uniqueidentifier. NEWID() involves random activity, thus the next value is unpredictable, and it’s slower to execute. NEWSEQUENTIALID() doesn’t involve random activity, thus the next generated value can be predicted (not easily!) and executes faster than NEWID(). So, if you’re not concerned about the next value … Read more
You need to be specific whether you want this operation happen asynchronously or not. As an example for Async Operation : public async Task<bool> login(string usn, string pwd) { DataClasses1DataContext auth = new DataClasses1DataContext(); var message = await (from p in auth.Users where p.usrName == usn && p.usrPass == pwd select p); if (message.Count() > … Read more
BEGIN and END deal with code blocks. They are similar to the curly braces you see in many languages: if (somethingIsTrue) { // like BEGIN // do something here } // like END In SQL, this is: if somethingIsTrue BEGIN — do something here END BEGIN TRAN, COMMIT, and ROLLBACK begin and end transactions. They … Read more
You are projecting three columns in your subquery, but comparing a single one of them in the IN clause. Select just the required column (r1.king) for the IN in the subquery: SELECT kingdom.king, dinasty.birth, dinasty.death FROM kingdom, dinasty WHERE kingdom.king = dinasty.name AND kingdom.king NOT IN ( SELECT DISTINCT R1.king FROM ( SELECT DISTINCT R1.king, … Read more
The documentation says about now(): now() is a traditional PostgreSQL equivalent to transaction_timestamp() And about transaction_timestamp(): These SQL-standard functions all return values based on the start time of the current transaction So within one SQL statement, now() will always return the same value.
Start with this: select StudentId, max(DateApproved) from tbl group by StudentId Then integrate that to main query: select * from tbl where (StudentId, DateApproved) in ( select StudentId, max(DateApproved) from tbl group by StudentId ) You can also use this: select * from tbl join (select StudentId, max(DateApproved) as DateApproved from tbl group by StudentId) … Read more
Filtering is one way to do this, as discussed in other answers. Filtering is not scalable though. On the surface time complexity would appear to be O(n) (i.e. already not scalable if the number of objects in the collection will grow), but actually because one or more tests need to be applied to each object … Read more
In SSMS, right-click on the table node and “Script Table As”https://stackoverflow.com/”Create”. There is no built in ‘script this table’ T-SQL. sp_help ‘tablename’ gives useful table information if that’d do.
No, you can only truncate a single table with TRUNCATE command. To truncate multiple tables you can use T-SQL and iterate through table names to truncate each at a time. DECLARE @delimiter CHAR(1), @tableList VARCHAR(MAX), @tableName VARCHAR(20), @currLen INT SET @delimiter=”,” SET @tableList=”table1,table2,table3″ WHILE LEN(@tableList) > 0 BEGIN SELECT @currLen = ( CASE charindex( @delimiter, … Read more
I am assuming that you are using latest version of Dapper. With Dapper, there are two ways to manage connection: Fully manage yourself: Here, you are fully responsible for opening and closing connection. This is just like how you treat connection while working with ADO.NET. Allow Dapper to manage it: Dapper automatically opens the connection … Read more