Most Elegant Way to Populate Nulls from Reference Table
I have two tables like so:
Column 1 Column 2 A 1 B NULL C 3 D 4
Column 1 Column 2 A 1 B 2 C 3 D 4
I receive the data in table 2 on a time delay, and what I need to do when I receive it is populate the null values in Table 1 with the data in table 2. Is there an elegant way to do this in Standard SQL without making temporary tables or using sub-queries?
Consider using a MERGE statement:
MERGE dataset.table1 AS t1 USING dataset.table2 AS t2 ON t1.column1 = t2.column1 WHEN MATCHED THEN UPDATE SET t2.column2 = t1.column2
Take a look at the supported actions you can perform; if you want to insert new rows, you can do that using MERGE as well.
T-SQL Querying, the CROSS APPLY operator, and then refer to it in the query's WHERE clause, like This query generates the following output where the rows with a NULL in the more elegant way to achieve unpivoting compared to the previous method. a task, I'll use a table called Sales that you create and populate by running the CLR nullable value types are not intended for storage of database nulls because an ANSI SQL null does not behave the same way as a null reference (or Nothing in Visual Basic). For working with database ANSI SQL null values, use System.Data.SqlTypes nulls rather than Nullable .
It is not clear from your question how you receive data from Table 2, so I will assume that you have a temporary table called
Table2. You will have to
Table2 in order to find which rows have NULL values, i.e
Table1.Column2 IS NULL. Then update
Column2 in those rows using the value in
Table2. It should be something like this:
UPDATE Table1 SET Column2 = Table2.Column2 FROM Table1 LEFT JOIN Table2 USING(Column1) WHERE Table1.Column2 IS NULL
Office Automation: Concepts and Tools, (TLA stands for "Three Letter Acronym", and, unlike most acronyms, requires no apologies.) He can then process the forms and file them or send them on their way. Reference tables and calculating tools are made available through an of "smart forms", which automatically fill certain fields using previously filled-in fields I have a table that has 4 columns: Item, Year, Month, Amount. Some of the values for Amount are null and when that happens I want to fill those values in with the previous Amount value that is not null. I can easily do this with the LAG function when there is only one null value but when there are multiple in a row I am not sure how to approach it.
Correct use of UPDATE statement would be
UPDATE `project.dataset.table1` a SET Column_2 = b.Column_2 FROM `project.dataset.table2` b WHERE a.Column_1 = b.Column_1 AND a.Column_2 IS NULL
Migrating to Android for iOS Developers, Table 8-2 lists some common types or syntax in both languages. Java Syntax or Symbols Objective-C Java Object reference * N/A (delete them) Self self. this. NSUInteger Integer Null (undefined) value nil null Object id or NSObject Object Method For example, if you are populating a screen with many UILabels, your \$\begingroup\$ @G_A Rest assured, you can be sure that pair.Value will always return a string or a null reference. The only things that the ToString() call adds is the overhead of an extra method call (possibly optimized away, but not necessarily) and the possibility of a NullReferenceException. \$\endgroup\$ – phoog Jan 9 '13 at 3:49
InfoWorld, Where you intend to reference a label in another module, you can identify it as external to the program. to fill a block with a specified number of characters, such as nulls or spaces. You can nest as many as four files, one included file including yet another. The cross-reference table can print a list of all the line numbers You can leave the FK to some dimension tables as NULL if those dimensions are not known or not applicable. You just have to remember to use outer joins when you do your reporting query. Alternatively, some people create a "none" and/or an "n/a" dimension record for data mart dimensions and then populate fact table FKs to point at these rather
The Round Table: A Saturday Review of Politics Finance, , To her we refer the palpitating reader who pants for further pictures of this peerless We fill this cup to one made up Of beastliness alone, The caitift' of his dastard There are four more stanzas as good as this, and the whole concludes: This is its subject could scarcely excel it in the way of polished and elegant sarcasm. Explanation of the above query: @n is a MySQL user variable. It starts out NULL, and is assigned a value on each row as the UPDATE runs through rows. Where number is non-NULL, @n is assigned the value of number.
Scientific American, With or without fill! on loose counterahaft. within the rear of all. a- Write for full particulars. With one illustration. ntained III QPIIN'I'IFK' AMIRII'AN SUPPLEMENT. Null. A most useful little bound book of 150 pages. comprising. probably. the most Medallion Portraits of Distinguished American Inventors; Valuable Tables The ILE RPG Reference guide has a section entitled "Database Null Value Support," which details a plethora of implications related to this behavior. Keyed Operations Keyed operations (like SETLL, READE, and CHAIN) involving one or more NULL-capable key fields are simple, as long as your key list is defined correctly.