Correlated subqueries containing Transact-SQL outer joins. in PDF format, and may also contain other documents or updated information not which users must resort to a programming language to accomplish a desired task . SQL Server T-SQL is based on standards created by the American. National will find that T-SQL is a very versatile and powerful programming language. Several people contributed to the T-SQL Querying and T-SQL Programming . advanced T-SQL querying, query tuning, and programming in Microsoft SQL.
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PDF version of T-SQL Tutorial with content of Stored Procedures, SQL tutorial, Cursors, Triggers, Views, Functions, Data Types, Table Joins, Transactions, Interview Questions. T-SQL Select Query. T-SQL Stored Procedures. T-SQL for BI practitioners. CHAPTER 9 ) and parts of Inside Microsoft SQL Server T-SQL Programming (Microsoft. Press, ), this book. Although Transact-SQL has programming language features, you'd never want advantage to programming in Transact-SQL is that your routines execute on.
Example below. Applications are more maintainable and may experience a slight performance improvement if object references are schema qualified. However, attention to detail is imperative so that such delimited files are not taken as characters being embedded as valid data within a text or large variable character column. Write comments to aid the reader of the code. In a development environment, the developer testing the package may own the package but in all other environments SA System Administrator owns the package. The reason for execution plan is to determine whether an index is required.
Object Maintenance Documentation Include object maintenance documentation in every source code file. Keep this documentation current on all revisions after moving any given of this source file into a different location. Comment Quality Comments must contain a description of the process the SQL module source file , procedure, or trigger accomplishes. Write the description in clear, concise, non-colloquial English, using business terms to describe the processes.
Do not use comments such as: This is important because most developers can read the SQL and see line-by-line what it does mechanically, but may not be able to easily grasp the purpose business logic behind the code.
Write comments to aid the reader of the code. Comment Quantity More comments are better than using fewer comments. Remember that the code is reviewed first, then, over time perhaps after many years , require revisions and enhancements. Providing adequate comments allows the database SQL developer, and peers to quickly understand the logic and perform necessary revisions, and so forth.
Standard Object Header Every object contains an object header. An object header contains the database name, object name, creation date, author, a brief description of the object, parameters passed, returns, calling mechanism, tables and aliases used in code, other procedures called, DPSR , notes, and any special comments and warnings.
Module headers remain open on the right-hand side. The method involves using a maintenance documentation heading and comments within the source code. A common developer signature provides these together.
Object Maintenance Documentation Immediately following the object header there is a skeletal maintenance block. Use this skeletal block as a template for maintenance done to the object code.
Copy, paste, and fill in this block when you alter the object code. The block copy marks are on the lines with the equal signs. Include the lines with the block copy marks. Make the insertion of the copied block directly after the skeleton block. Thus, the history is recorded from earliest to latest. Examples of this illegal style follow: An example follows: Tab Stops Set tabs to either four spaces or eight spaces default.
Line Length Do not write a Transact-SQL line that exceeds characters in length, unless there is no other way to properly format the source. Line Count—needs moved to store proc section. Do not write procedures that exceed four pages in length excluding comments, headers, and maintenance log, without written justification to the data base administrators.
Exceptions to rule are procedures used in conversion or loads of data. Code exceeding this limit should be looked at closer and possibly split into smaller stored procedures or modularized.
This is prohibited. In all instances, include the appropriate fields in the statements where needed. An example of the wrong way to write a Transact-SQL statement follows: Example below. Specify each field as in the examples: FirstName, psn. LastName, emp. Person AS psn ON emp. Formatting rules for this structure are as follows: No exceptions are permitted. It is best to apply this style even when you do not exceed the character limit though this rule is not strictly enforced.
The guidelines presented here by example apply to all Transact-SQL statements. Use of white space is highly recommended. Person psn ON emp. Individual elements are placed in separate lines 2. Elements are indented one tab stop 3.
If the length of the keyword or keywords ex: Parentheses are used to distinguish logical blocks and are indented at the same level as any other parameter. Other examples follow: Example of Select Statement: To ensure consistency parameters are descriptive and define correctly according to their usage.
Second example is to check a range.
The advantages include: Stored procedures are named according to the business function they perform or business rule they enforce. The name should include a prefix of BS for BroadStone and a business description of the action performed.
The name is appropriately abbreviated with items found in the standard abbreviation list. All stored procedures, begin with one of the following: This means one insert, one update or one delete statement per stored procedure. Do not write stored procedures that exceed four pages in length excluding comments, headers, and maintenance log.
Exceptions to the rule are procedures used in conversion or loads of data. Analyse code exceeding this limit and split into smaller stored procedures or modularize.
The comment block is simple and contains a brief audit listing of changes that go to production; not a running summary of changes during development.
Error Trapping is highly recommended with the Enterprise libraries, because if you have an error, the first thing one ask is what the error log says.
Please also list the fields. Also, white space for readability is also highly desirable.
StoredProcedure [P3Schema]. StoredProcedure [BS]. Harry Potter Procedure Desc: This procedure creates new bsu for existing admission. This is acceptable: The above and latter is supported by industry standards. Triggers Triggers are to be avoided as they have the potential to cause execute multiple SQL statements without other developer knowledge.
Constraints Planning and creating tables requires identifying how to enforce integrity of the data stored within the columns of the tables. Primary Key Constraints are columns or a column that uniquely identifies a row within a table.
All tables should have a primary key and composite primary keys should be avoided. For most of your OLTP tables, an identity column is the primary key.
Foreign Key Constraints are columns or a column that is used to enforce a relation between information in two tables. A link is defined between the two tables when a primary key is referenced by a column or columns in another table. The reference becomes a foreign key in the second table. Indexes An index is an on-disk structure associated with a table or a view that speeds retrieval of rows from the table or the view.
An index contains keys built from one or more columns in the table or the view. These keys are stored in a structure B-tree that enables SQL Server to find the row or rows associated with the key values quickly and efficiently. A table or view can contain the following types of indexes: These are the columns included in the index definition.
There can be only one clustered index per table, because the data rows themselves can be sorted in only one order. When a table has a clustered index, the table is called a clustered table. If a table has no clustered index, its data rows are stored in an unordered structure called a heap.
A nonclustered index contains the nonclustered index key values and each key value entry has a pointer to the data row that contains the key value.
The structure of the row locator depends on whether the data pages are stored in a heap or a clustered table. For a heap, a row locator is a pointer to the row. For a clustered table, the row locator is the clustered index key. The default value is used when inserting a new row in a table and a particular column in the insert statement does not have a value.
For example you may have a default of all that you may want to set up as a default end date. User defined functions are created and used for actions repeated within an application. An example is adding dashes to social security number.
This user defined function could be created and used any time a correctly formatted social security number is required. If the END CATCH statement is the last statement in a stored procedure or trigger, control is returned to the code that invoked the stored procedure or trigger. SQL has been around for many years and it will be around for many more coming years. It is also one of the matured technology, hence there are a lot of free resources e. I have been sharing some free eBooks on different technologies e.
Some of the books are available for free to read online others you can download in PDF format. These are the books which are made available free from publisher and authors for the benefit of the community. You can either download their PDF version for offline reading or you can read them online.
Use the Index, Luke! Markus Winand Download: This book is for developers; it avoids unnecessary details about database internals. That's all in this list of Free SQL books for beginners and experienced developers.