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Is there any performance gain in indexing a boolean field?
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It depends on the actual queries and the selectivity of the index/query combination.
Case A: condition WHERE isok = 1 and nothing else there:
SELECT *
FROM tableX
WHERE isok = 1
If the index is selective enough (say you have 1M rows and only 1k have isok = 1), ...
T-SQL query to show table definition?
...n get most of the details from Information Schema Views and System Views.
SELECT ORDINAL_POSITION, COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH
, IS_NULLABLE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'Customers'
SELECT CONSTRAINT_NAME
FROM INFORMATION_SCHEMA.CONSTRAINT_TABLE_US...
How to insert text into the textarea at the current cursor position?
...ction insertAtCursor(myField, myValue) {
//IE support
if (document.selection) {
myField.focus();
sel = document.selection.createRange();
sel.text = myValue;
}
//MOZILLA and others
else if (myField.selectionStart || myField.selectionStart == '0') {
...
jQuery datepicker set selected date, on the fly
How can I change the selected date of jquery Date picker dynamically on the fly?
I have say created a inline date picker.
Then after some time, I want to reflect a different date there without recreating the datepicker from the scratch.
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How to get the Full file path from URI
...but if i do it like the MediaStore Solution, it won't work if the app user selects eg Astro as browser, instead of Music Player. How do I solve this?
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How can I shift-select multiple checkboxes like GMail?
... can click on one checkbox in the email list, hold down the Shift key, and select a second checkbox. The JavaScript will then select/unselect the checkboxes that are between the two checboxes.
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How to get Top 5 records in SqLite?
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SELECT * FROM Table_Name LIMIT 5;
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How to drop columns by name in a data frame
..."z","u"))]
x y
1 1 2
2 2 3
3 3 4
4 4 5
5 5 6
Or, much simpler, use the select argument of the subset function : you can then use the - operator directly on a vector of column names, and you can even omit the quotes around the names !
R> subset(df, select=-c(z,u))
x y
1 1 2
2 2 3
3 3 4
4 4 ...
Select second last element with css
I already know of :last-child. But is there a way to select the div:
2 Answers
2
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What GRANT USAGE ON SCHEMA exactly do?
...a schema doesn't grant rights on the tables within.
If you have rights to SELECT from a table, but not the right to see it in the schema that contains it then you can't access the table.
The rights tests are done in order:
Do you have `USAGE` on the schema?
No: Reject access.
Yes: Do...