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Explicit vs implicit SQL joins
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Personally I prefer the join syntax as its makes it clearer that the tables are joined and how they are joined. Try compare larger SQL queries where you selecting from 8 different tables and you have lots of filtering in the where. By using join syntax you separate out the parts where the tabl...
This Row already belongs to another table error when trying to add rows?
I have a DataTable which has some rows and I am using the select to filter the rows to get a collection of DataRows which I then loop through using foreach and add it to another DataTable, but it is giving me the error "This Row already belongs to another table". Here is the code:
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SQL Server Management Studio won't let me add an index to a table
When I right click on the indexes folder in the table the "New Index" menu item is grayed out. I don't understand why. I've deleted all data in the table just in case, and refreshed and restarted SSMS, but no luck. I'm using SQL Server 2012 Business Intelligence SP1 CTP.
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How does a hash table work?
I'm looking for an explanation of how a hash table works - in plain English for a simpleton like me!
15 Answers
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Why does X[Y] join of data.tables not allow a full outer join, or a left join?
This is a bit of a philosophical question about data.table join syntax. I am finding more and more uses for data.tables, but still learning...
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How to shrink/purge ibdata1 file in MySQL
... is, everytime I run a R script, I create a new database (A), create a new table (B), import the data into B, submit a query to get what I need, and then I drop B and drop A.
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What replaces cellpadding, cellspacing, valign, and align in HTML5 tables?
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/* cellpadding */
th, td { padding: 5px; }
/* cellspacing */
table { border-collapse: separate; border-spacing: 5px; } /* cellspacing="5" */
table { border-collapse: collapse; border-spacing: 0; } /* cellspacing="0" */
/* valign */
th, td { vertical-align: top; }
/* align (center) ...
How to create a DataTable in C# and how to add rows?
How do create a DataTable in C#?
13 Answers
13
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MySQL - Rows to Columns
...e of terms that I'll use for the rest of this post. This will be the base table:
select * from history;
+--------+----------+-----------+
| hostid | itemname | itemvalue |
+--------+----------+-----------+
| 1 | A | 10 |
| 1 | B | 3 |
| 2 | A | ...
Is 'switch' faster than 'if'?
...ons a compiler can make on a switch. I don't think the oft-mentioned "jump-table" is a very useful one though, as it only works when the input can be bounded some way.
C Pseudocode for a "jump table" would be something like this -- note that the compiler in practice would need to insert some form o...