It's usually when folks build up SQL statements.
When you add and value = "Toyota" you don't have to worry about whether there is a condition before or just WHERE. The optimiser should ignore it
No magic, just practical
Example Code:
commandText = "select * from car_table where 1=1";
if (m...
Table Variables don't have statisics in the same way as Temp Tables normally they're assumed to have only 1 row. This incorrect estimate of rowcount will make a nested loop operation look like the best plan but when this is done for a larger amount of rows the cost can easier be greater than a t...
It really depends on whether the developer has any support responsibilities. If they are on the hook for third line support then they will probably need to look at the production database to do this.
Generally it's a bad idea to do anything on a production server unless it's really necessary to...
I made a comment yesterday about it when 4 high rep people on SO all answered the same really basic question
answers that contain information that most folks don't know but can easily grasp seem to get the most votes, it's easy for them to read it, say "OH YEAH!" and upvote
SQL excels at analyzing large sets of relational data.
The place to draw the line is the scale of your analysis.
If you analyze individual records one at a time, do it in your application.
If you analyze large sets of records as a unit, SQL is definitely the best tool for that job.
Row-by-ro...
I'm not sure how you got that first one. For me, for that query, I would use:
CREATE NONCLUSTERED INDEX NC_EmpDep
ON Employee(DepartmentID)
INCLUDE (EmployeeID, Lastname)
There's not a "Hard and fast rule" for pretty much anything in SQL.
But, for your example, the only field the index ...
gbn had highest score on that Q, but nobody really gets indexing so none of them got many votes
SQL Server optimises the process of compilation of the query plan for the stored procedure by ignoring the conditional branches inside the stored procedure. The plan will be generated based on the parameters used for the first execution, this will cause problems if the parameters are different f...
A fully working example (for SQL Server 2005+)
If you need it for another system, there are equivalents for the pieces of the puzzle below
row_number()
dense_rank()
un/pivot
You can find the equivalents from other Stackoverflow questions. For example, the first two are well supported by Oracl...
It's usually when folks build up SQL statements.
When you add and value = "Toyota" you don't have to worry about whether there is a condition before or just WHERE. The optimiser should ignore it
No magic, just practical
Example Code:
commandText = "select * from car_table where 1=1";
if (m...
SQL excels at analyzing large sets of relational data.
The place to draw the line is the scale of your analysis.
If you analyze individual records one at a time, do it in your application.
If you analyze large sets of records as a unit, SQL is definitely the best tool for that job.
Row-by-ro...
A fully working example (for SQL Server 2005+)
If you need it for another system, there are equivalents for the pieces of the puzzle below
row_number()
dense_rank()
un/pivot
You can find the equivalents from other Stackoverflow questions. For example, the first two are well supported by Oracl...
