Mike and Doris Manning
mikedorism at ntelos.net
Mon Oct 6 15:36:09 CDT 2003
Pardon me, but I need to correct myself. Char -- fixed width -- padded with spaces VarChar -- variable width -- no padding NChar -- fixed width allowing for Unicode characters -- padded with spaces NVarChar -- variable width allowing for Unicode characters -- no padding >From SQL BOL: The Unicode specification defines a single encoding scheme for most characters widely used in businesses around the world. All computers consistently translate the bit patterns in Unicode data into characters using the single Unicode specification. This ensures that the same bit pattern is always converted to the same character on all computers. Data can be freely transferred from one database or computer to another without concern that the receiving system will translate the bit patterns into characters incorrectly. One problem with data types that use 1 byte to encode each character is that the data type can only represent 256 different characters. This forces multiple encoding specifications (or code pages) for different alphabets such as European alphabets, which are relatively small. It is also impossible to handle systems such as the Japanese Kanji or Korean Hangul alphabets that have thousands of characters. Each MicrosoftR SQL ServerT collation has a code page that defines what patterns of bits represent each character in char, varchar, and text values. Individual columns and character constants can be assigned a different code page. Client computers use the code page associated with the operating system locale to interpret character bit patterns. There are many different code pages. Some characters appear on some code pages, but not on others. Some characters are defined with one bit pattern on some code pages, and with a different bit pattern on other code pages. When you build international systems that must handle different languages, it becomes difficult to pick code pages for all the computers that meet the language requirements of multiple countries/regions. It is also difficult to ensure that every computer performs the correct translations when interfacing with a system using a different code page. The Unicode specification addresses this problem by using 2 bytes to encode each character. There are enough different patterns (65,536) in 2 bytes for a single specification covering the most common business languages. Because all Unicode systems consistently use the same bit patterns to represent all characters, there is no problem with characters being converted incorrectly when moving from one system to another. You can minimize character conversion issues by using Unicode data types throughout your system. Doris Manning Database Administrator Hargrove Inc. www.hargroveinc.com -----Original Message----- From: dba-sqlserver-bounces at databaseadvisors.com [mailto:dba-sqlserver-bounces at databaseadvisors.com] On Behalf Of John Colby Sent: Monday, October 06, 2003 1:18 PM To: dba-sqlserver at databaseadvisors.com Subject: RE: [dba-SQLServer]Field Sizes >It does if you use varchar (pads the rest with spaces) but it does not >if you use nvarchar. Which begs the question, why use varchar? Faster than Nvarchar? John W. Colby www.colbyconsulting.com -----Original Message----- From: dba-sqlserver-bounces at databaseadvisors.com [mailto:dba-sqlserver-bounces at databaseadvisors.com]On Behalf Of Mike and Doris Manning Sent: Monday, October 06, 2003 1:16 PM To: dba-sqlserver at databaseadvisors.com Subject: RE: [dba-SQLServer]Field Sizes It does if you use varchar (pads the rest with spaces) but it does not if you use nvarchar. Doris Manning Database Administrator Hargrove Inc. www.hargroveinc.com -----Original Message----- From: dba-sqlserver-bounces at databaseadvisors.com [mailto:dba-sqlserver-bounces at databaseadvisors.com] On Behalf Of John Colby Sent: Monday, October 06, 2003 9:59 AM To: SQLServer Subject: [dba-SQLServer]Field Sizes Access stores text and memo data using the exact amount needed (plus pointers) , i.e. even though the text field says 255 characters if the string is 10 characters, 10 characters are used for storage. Does SQL Server work this way of is space "reserved" for the stated size of the field? John W. Colby www.colbyconsulting.com _______________________________________________ dba-SQLServer mailing list dba-SQLServer at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-sqlserver http://www.databaseadvisors.com _______________________________________________ dba-SQLServer mailing list dba-SQLServer at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-sqlserver http://www.databaseadvisors.com _______________________________________________ dba-SQLServer mailing list dba-SQLServer at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-sqlserver http://www.databaseadvisors.com