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06-30-09, 06:27
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Registered User
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Join Date: Jun 2009
Posts: 7
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How convert data in database?
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Hi alll
i want to convert raw data using math function to voltage value.That function giving as x*625/1024. x =raw data. That converting process happen in PostgreSQL database.But how to do it?TQ all.
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06-30-09, 18:37
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Super Moderator
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Join Date: Jun 2004
Location: Arizona, USA
Posts: 1,775
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Create a new table, identical to the original table, except with voltage field.
Insert data into the new table, using a subselect in the insert statement. Something along the lines of:
Code:
Insert into NewTable (Field1, Field2, ... Voltage)
Select OldTable.Field1, OldTable.Field2, ... OldTable.RawData * 625/1024 as Voltage
__________________
Lou
使大吃一惊
"Lisa, in this house, we obey the laws of thermodynamics!" - Homer Simpson
"I have my standards. They may be low, but I have them!" - Bette Middler
"It's a book about a Spanish guy named Manual. You should read it." - Dilbert
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Last edited by loquin; 06-30-09 at 18:41.
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07-01-09, 07:39
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Registered User
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Join Date: Jun 2009
Posts: 7
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tq loquin,
but raw value still not change to voltage value after refreshed.i give the code below.what wrong?
Code:
DELETE FROM mts400_results_l
WHERE mts400_results_l.nodeid = new.nodeid;
INSERT INTO mts400_results_l(result_time, epoch, nodeid, parent, voltage, humid, humtemp, prtemp, press, taosch0, taosch1, accel_x, accel_y)
VALUES (new.result_time, new.epoch, new.nodeid, new.parent, new.voltage, new.humid, new.humtemp, new.prtemp, new.press, new.taosch0, new.taosch1, new.accel_x, new.accel_y);
SELECT mts400_results_l.voltage* 625/1024 AS voltage
Code:
SELECT mts400_results_l.voltage* 625/1024 AS voltage
that customised code not work?compilling not have any problem but nothing change in data.still same.tq very much for who can helping me...
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07-01-09, 20:19
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Super Moderator
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Join Date: Jun 2004
Location: Arizona, USA
Posts: 1,775
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Create a new table with the same fields as the existing table.
Insert into the NEW table, using a sub-select from the original table as the source for the select.
You can also use the Create Table As syntax to create a table which contains data from a select...
Code:
CREATE TABLE mts400_results_NEW AS
Select result_time, epoch, nodeid, parent, voltage * 625/1024 as voltage, humid, humtemp, prtemp, press, taosch0, taosch1, accel_x, accel_y
From mts400_results_1
From a safety viewpoint, I would not try to update the data 'in place.' Create the new table, copy the old data into the new table, processing the voltage as you do so.
Then, after you verify that the voltage data is correct, use the new table as a data source for updating the existing table
__________________
Lou
使大吃一惊
"Lisa, in this house, we obey the laws of thermodynamics!" - Homer Simpson
"I have my standards. They may be low, but I have them!" - Bette Middler
"It's a book about a Spanish guy named Manual. You should read it." - Dilbert
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07-03-09, 07:08
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Registered User
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Join Date: Jun 2009
Posts: 7
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Code:
CREATE RULE "cache_mts400_results" AS ON INSERT TO "public"."mts400_results"
always get error with this code.what wrong?
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Last edited by dukati; 07-03-09 at 07:23.
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How convert data in database?
