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MySQL: determine which database is selected?
After calling mysql_select_db to grab a database, is there any way to later output the name of the database that is currently selected? This seems very basic but I couldn't find anything on php.net or stackoverflow (all results are for "no database selected").
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How to search a specific value in all tables (PostgreSQL)?
... If you're using IntelliJ you can just right-click your db and select "Dump with 'pg_dump'" or "Dump data to file(s)"
– Laurens
Nov 29 '17 at 12:26
3
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Oracle Differences between NVL and Coalesce
...the first non-NULL (there are some exceptions, such as sequence NEXTVAL):
SELECT SUM(val)
FROM (
SELECT NVL(1, LENGTH(RAWTOHEX(SYS_GUID()))) AS val
FROM dual
CONNECT BY
level <= 10000
)
This runs for almost 0.5 seconds, since it generates...
Bootstrap select dropdown list placeholder
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Yes just "selected disabled" in the option.
<select>
<option value="" selected disabled>Please select</option>
<option value="">A</option>
<option value="">B</option>
<optio...
How do I use ROW_NUMBER()?
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For the first question, why not just use?
SELECT COUNT(*) FROM myTable
to get the count.
And for the second question, the primary key of the row is what should be used to identify a particular row. Don't try and use the row number for that.
If you returned Ro...
UITableview: How to Disable Selection for Some Rows but Not Others
... able to click it at all) The table contains two groups. I want to disable selection for the first group only but not the second group. Clicking the first row of second group navigates to my tube player view .
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1052: Column 'id' in field list is ambiguous
...and tbl_section which has both the id field in them. How do I go about selecting the id field, because I always get this error:
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Insert into … values ( SELECT … FROM … )
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Try:
INSERT INTO table1 ( column1 )
SELECT col1
FROM table2
This is standard ANSI SQL and should work on any DBMS
It definitely works for:
Oracle
MS SQL Server
MySQL
Postgres
SQLite v3
Teradata
DB2
Sybase
Vertica
HSQLDB
H2
AWS RedShift
SA...
Saving enum from select in Rails 4.1
...num.
I changed the input to be the following:
f.input :color, :as => :select, :collection => Wine.colors.keys.to_a
Which generated the following HTML:
<select id="wine_color" name="wine[color]">
<option value=""></option>
<option value="red">red</option>
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Is there a way to access the “previous row” value in a SELECT statement?
...d to order by some column for this to be meaningful. Something like this:
select t1.value - t2.value from table t1, table t2
where t1.primaryKey = t2.primaryKey - 1
If you know how to order things but not how to get the previous value given the current one (EG, you want to order alphabetically) ...