sqlserver 全角 半角 変換: A Tale of Characters and Conversion

In the vast and mysterious world of SQL Server, there lies a story of characters and conversion. This tale revolves around a peculiar problem faced by a database administrator named Ken. Ken’s journey is filled with challenges as he navigates through the intricacies of SQL Server, specifically in dealing with the conversion between full-width and half-width characters.Story OverviewKen, a seasoned database administrator, was tasked with managing a database that contained a mix of full-width and half-width characters. This database served as the backbone for various applications, and any mishandling of these characters could lead to significant data inconsistencies. Ken’s mission was to ensure that all characters were correctly converted to maintain the integrity of the data.Plot IntroductionKen embarked on a quest to address the issue of full-width and half-width characters within the database. He began by analyzing the data to understand the extent of the problem. He discovered that certain tables contained a high percentage of full-width characters, which could cause issues in queries and reporting.Ken’s first step was to identify the tables and columns affected by the character conversion issue. He used SQL Server’s built-in functions to detect the presence of full-width characters. The SQL query he used was as follows:“`sqlSELECTtable_name,column_name,COUNT(*) AS full_width_countFROMINFORMATION_SCHEMA.COLUMNSJOINsys.columns ON INFORMATION_SCHEMA.COLUMNS.column_name = sys.columns.nameJOINsys.tables ON INFORMATION_SCHEMA.COLUMNS.table_name = sys.tables.nameWHEREDATA_TYPE LIKE ‘%char%’ OR DATA_TYPE LIKE ‘%varchar%’AND EXISTS (SELECT 1FROM sys.fn_infnchar(sys.columns.column_id, sys.columns.object_id, 1, ‘ ‘)WHERE col1 = 0x81)GROUP BYtable_name,column_name“`Character Conversion TechniquesArmed with the information, Ken decided to apply various techniques to convert the full-width characters to half-width. He utilized the `REPLACE` function in SQL Server to perform the conversion. The following query demonstrates how Ken could convert the full-width space (0x81) to a half-width space (0x20):“`sqlUPDATEtarget_tableSETcolumn_name = REPLACE(column_name, 0x81, 0x20)FROMtarget_tableJOINsys.columns ON target_table.object_id = sys.columns.object_id AND target_table.column_id = sys.columns.column_idJOINsys.tables ON target_table.object_id = sys.tables.object_idWHEREcolumn_name LIKE ‘%0x81%’“`Apostrophes and Other CharactersKen also encountered challenges with apostrophes and other special characters. He used the `CHAR` function to replace these characters with their half-width counterparts. For example, to convert a full-width apostrophe (0x80) to a half-width apostrophe (0x27), he used the following query:“`sqlUPDATEtarget_tableSETcolumn_name = REPLACE(column_name, 0x80, 0x27)FROMtarget_tableJOINsys.columns ON target_table.object_id = sys.columns.object_id AND target_table.column_id = sys.columns.column_idJOINsys.tables ON target_table.object_id = sys.tables.object_idWHEREcolumn_name LIKE ‘%0x80%’“`ConclusionWith the successful conversion of full-width to half-width characters, Ken’s database was now free from inconsistencies. The applications that relied on the database ran smoothly, and the database administrator could finally breathe a sigh of relief. The journey to convert full-width and half-width characters in SQL Server was a testament to the resilience and expertise of database administrators in handling complex data challenges.Video Screenshots1. Ken analyzing data with SQL Server Management Studio.2. Query execution results showing the presence of full-width characters.3. SQL query being executed to convert full-width characters to half-width.4. Final database tables after conversion, with clear and consistent data.This story of characters and conversion in SQL Server is a reminder of the importance of data integrity and the challenges faced by database administrators in maintaining it.