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1. RED GATE SQL DATA GENERATOR OTHER TABLE COLUMN UPDATE
2. RED GATE SQL DATA GENERATOR OTHER TABLE COLUMN FULL

You must also qualify a column with a table alias, rather than rely on the table name, if it is in a table that is being used twice in a JOIN. Of course, if the table really has illegal characters, then a table alias provides a blessed relief from those pesky square brackets.

RED GATE SQL DATA GENERATOR OTHER TABLE COLUMN FULL

For example, if you don’t give a table variable an alias, then you must provide the square bracket delimiters to refer to it by its full name. You might look outraged and say you’d never stoop so low as to do that, but on the other hand isn’t legal at the start of a table name qualifier, so table variables are a problem. One reason for needing to use an alias is when the name of the base table has illegal characters in it. If it doesn’t, then it just gets in the way. In general terms, if a table source has already got a suitable name, then why provide another? Almost always, you do it only to make your query clearer in its intention. The use of aliases is only obligatory if you are referencing a table source that doesn’t have a name, such as a derived table or rowset function, or if you are using a named table source, such as a table, view or table-valued function, more than once in the same query. You can just use the name of the table source that supplied the column. To qualify a column to its table, you generally don’t have to use table aliases (also known as correlation names in ANSI SQL). However, if there are no JOIN clauses, then the adding any sort of table qualifier, alias or not, to the column name is entirely superfluous and shouldn’t be used. With SQL Server, the use of the qualified column names makes things easier for the parser anyway and makes the query easier to read.

In SQL, you only need to qualify column names with the reference to the table source if the column name by itself is ambiguous, in that it could have come from one or more table sources in the FROM clause. Do I always need to qualify column names? It is only that reference that is aliased. When you use a table alias, you are just providing a specific name for the instance of a table reference, not the actual table.

RED GATE SQL DATA GENERATOR OTHER TABLE COLUMN UPDATE

It would be truer to say that you can only use them in statements that have a FROM clause, because SQL Server has syntax that allows it to use a FROM clause in UPDATE and DELETE statements.

In standard SQL, aliases are only used in SELECT statements. It just means that it is up to the database developer to improve that default alias to provide meaning. It doesn’t do it because short meaningless names are better. If you enable its Assign aliases option, SQL Prompt will auto-suggest one-character or two-character aliases, as you type in your SQL statements, just because it must provide something but cannot provide meaning. This is especially true if you are using SQL Prompt because it does all that typing for you.

Aliases aren’t there to make it easier and faster to type in SQL queries. The primary purpose of table aliases, aside from cases where they are required, is to make SQL queries easier to read and understand. He is a regular contributor to Simple Talk and SQLServerCentral.

Phil Factor (real name withheld to protect the guilty), aka Database Mole, has 30 years of experience with database-intensive applications.ĭespite having once been shouted at by a furious Bill Gates at an exhibition in the early 1980s, he has remained resolutely anonymous throughout his career. The tool can be used to generate test data from scratch or from existing data.This is a guest post from Phil Factor. Only a few simple entries are necessary to generate comprehensive (realistic) test data. It reads your database and displays tables and columns with their data generation settings. The tool can be used by DBAs, developers, or testers, who need sample data to test a database-driven application.ĭatanamic Data Generator makes database test data generation easy and painless. Writing your own test data generators or scripts is time consuming.