Oracle SQL Developer

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SQL and PL/SQL Programming with Unicode11.3.2.1 The NCHAR Data TypeWhen you define a table column or a PL/SQL variable as the NCHAR data type, thelength is always specified as the number of characters. For example, the followingstatement creates a column with a maximum length of 30 characters:CREATE TABLE table1 (column1 NCHAR(30));The maximum number of bytes for the column is determined as follows:maximum number of bytes =(maximum number of characters) x (maximum number of bytes for each character)For example, if the national character set is UTF8, then the maximum byte length is 30characters times 3 bytes for each character, or 90 bytes.The national character set, which is used for all NCHAR data types, is defined when thedatabase is created. The national character set can be either UTF8 or AL16UTF16. Thedefault is AL16UTF16.The maximum column size allowed is 2000 characters when the national character setis UTF8 and 1000 when it is AL16UTF16. The actual data is subject to the maximumbyte limit of 2000. The two size constraints must be satisfied at the same time. InPL/SQL, the maximum length of NCHAR data is 32767 bytes. You can define an NCHARvariable of up to 32767 characters, but the actual data cannot exceed 32767 bytes. Ifyou insert a value that is shorter than the column length, then Oracle pads the valuewith blanks to whichever length is smaller: maximum character length or maximumbyte length.Note: UTF8 may affect performance because it is a variable-widthcharacter set. Excessive blank padding of NCHAR fields decreasesperformance. Consider using the NVARCHAR data type or changingto the AL16UTF16 character set for the NCHAR data type.11.3.2.2 The NVARCHAR2 Data TypeThe NVARCHAR2 data type specifies a variable length character string that uses thenational character set. When you create a table with an NVARCHAR2 column, youspecify the maximum number of characters for the column. Lengths for NVARCHAR2are always in units of characters, just as for NCHAR. Oracle subsequently stores eachvalue in the column exactly as you specify it, if the value does not exceed the column'smaximum length. Oracle does not pad the string value to the maximum length.The maximum column size allowed is 4000 characters when the national character setis UTF8 and 2000 when it is AL16UTF16. The maximum length of an NVARCHAR2column in bytes is 4000. Both the byte limit and the character limit must be met, so themaximum number of characters that is actually allowed in an NVARCHAR2 column isthe number of characters that can be written in 4000 bytes.In PL/SQL, the maximum length for an NVARCHAR2 variable is 32767 bytes. You candefine NVARCHAR2 variables up to 32767 characters, but the actual data cannot exceed32767 bytes.The following statement creates a table with one NVARCHAR2 column whosemaximum length in characters is 2000 and maximum length in bytes is 4000.CREATE TABLE table2 (column2 NVARCHAR2(2000));11-20 SQL Developer Online Help
Locale-Dependent SQL Functions with Optional NLS Parameters11.3.3 Unicode String LiteralsYou can input Unicode string literals in SQL and PL/SQL as follows:■■Put a prefix N before a string literal that is enclosed with single quote marks. Thisexplicitly indicates that the following string literal is an NCHAR string literal. Forexample, N'résumé' is an NCHAR string literal. This has the same limitation asenclosing the string literal with single quote marks, where the data can be lostduring the conversion to the server's database character set. To avoid the potentialloss of data, you can set the environment variable ORA_NCHAR_LITERAL_REPLACE to true. This will transparently replace the N' internally and preservethe text literal for SQL processing. By default, this environment variable is set tofalse to maintain backward compatibility.Use the NCHR(n) SQL function, which returns a unit of character code in thenational character set, which is AL16UTF16 or UTF8. The result of concatenatingseveral NCHR(n) functions is NVARCHAR2 data. In this way, you can bypass theclient and server character set conversions and create an NVARCHAR2 stringdirectly. For example, NCHR(32) represents a blank character.Because NCHR(n) is associated with the national character set, portability of theresulting value is limited to applications that run with the same national characterset. If this is a concern, then use the UNISTR function to remove portabilitylimitations.■ Use the UNISTR('string') SQL function. UNISTR('string') converts a string tothe national character set. To ensure portability and to preserve data, include onlyASCII characters and Unicode encoding in the following form: \xxxx, wherexxxx is the hexadecimal value of a character code value in UTF-16 encodingformat. For example, UNISTR('G\0061ry') represents 'Gary'. The ASCIIcharacters are converted to the database character set and then to the nationalcharacter set. The Unicode encoding is converted directly to the national characterset.The last two methods can be used to encode any Unicode string literals.11.4 Locale-Dependent SQL Functions with Optional NLS ParametersAll SQL functions whose behavior depends on globalization support conventionsallow NLS parameters to be specified. These functions are:TO_CHARTO_DATETO_NUMBERNLS_UPPERNLS_LOWERNLS_INITCAPNLSSORTExplicitly specifying the optional NLS parameters for these functions enables thefunctions to be evaluated independently of the session's NLS parameters. This featurecan be important for SQL statements that contain numbers and dates as string literals.For example, the following query is evaluated correctly if the language specified fordates is AMERICAN:SELECT last_name FROM employees WHERE hire_date > '01-JAN-1999';Working in a Global Environment 11-21
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Oracle SQL DeveloperOnline HelpRele
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Contents1 SQL Developer Concepts an
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3.12 Create/Edit Index ............
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6.3.2 Updating Data With the UPDATE
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10.2.5 SQL*Plus SET Commands.......
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SQL Developer User InterfaceThe men
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SQL Developer User InterfaceThe Com
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Database Objects1.2 Database Object
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Database Objectscontaining the mast
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Database Objects■■■■■■
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Database ConnectionsWhen you start
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Running and Debugging Functions and
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Using the SQL WorksheetRelated Topi
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Using the SQL WorksheetScript Runne
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Using the SQL Worksheetmentioned in
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Reports1.9 ReportsRelated TopicsRun
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Reports1.9.3 Table reportsTable rep
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Reportsissues and vulnerabilities,
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SQL Developer Preferencesand the SQ
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SQL Developer Preferences1.10.3 Cod
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SQL Developer PreferencesSQL Develo
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SQL Developer User Information: Loc
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Supplementary Oracle Database Infor
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Creating a Table (Books)the table t
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Creating a Table (Transactions)Colu
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Creating a SequenceName: for_key_bo
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Creating a PL/SQL Procedure2.6 Crea
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Using the SQL Worksheet for Queries
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Script for Creating and Using the L
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Script for Creating and Using the L
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Check for UpdatesTo remove the effe
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Select Library3.8 Select LibraryThi
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Create PL/SQL Function, Procedure,
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Create Table (quick creation)Relate
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Create/Edit Table (with advanced op
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Create Type (User-Defined)For more
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Create/Edit ViewTest Syntax: Checks
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Configure File Type AssociationsDia
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Find/Replace TextTo add a type of o
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Save/Save As3.37 Save/Save As3.38 S
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SQL*Plus Location3-28 SQL Developer
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Managing TablesTo include lowercase
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Managing Tables4.2.4 Column Constra
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Managing Indexes4.3 Managing Indexe
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Managing Indexesuseful when all of
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Managing Views4.4 Managing Views4.3
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Managing Synonyms4-12 SQL Developer
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Storing Numeric Data■■NCHAR and
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Storing Numeric DataThe absence of
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Storing Datetime Data5.4.1.2 Using
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Storing Datetime Data5-8 SQL Develo
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Retrieving Data With Queries■■
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Retrieving Data With QueriesSee Als
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Retrieving Data With QueriesSee Als
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Transaction Control Statements6.3.2
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Using Pseudocolumns, Sequences, and
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Using SQL Data Definition Language
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Using SQL Data Definition Language
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Entering and Executing PL/SQL CodeY
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Utilizing the Main Features of PL/S
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Page 144 and 145: Utilizing the Main Features of PL/S
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Page 148 and 149: Handling PL/SQL ErrorsTo handle une
Page 150 and 151: Handling PL/SQL ErrorsIf you redecl
Page 152 and 153: Handling PL/SQL Errors7-26 SQL Deve
Page 154 and 155: Overview of Packages and Subprogram
Page 156 and 157: Managing Packagescalling procedures
Page 158 and 159: Oracle Product-Specific PackagesTab
Page 160 and 161: Oracle Product-Specific PackagesTab
Page 162 and 163: Oracle Product-Specific Packages8-1
Page 164 and 165: Overview of Triggers9.1.1 Types of
Page 166 and 167: Overview of Triggers■■A trigger
Page 168 and 169: Designing TriggersNote: A procedure
Page 170 and 171: Using SQL*Plus■■■Running Scri
Page 172 and 173: Using SQL*PlusA SQL script file is
Page 174 and 175: Using SQL*Plus10-6 SQL Developer On
Page 176 and 177: Overview of Globalization Support
Page 178 and 179: Setting up the Globalization Suppor
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Page 196 and 197: Locale-Dependent SQL Functions with
Page 198 and 199: Locale-Dependent SQL Functions with
Page 200 and 201: COLLECTION_IS_NULL exception, 7-22c
Page 202 and 203: overview, 7-14EXPLAIN PLANexecution
Page 204 and 205: NLSSORT SQL function, 11-21NO_DATA_
Page 206 and 207: displaying output from PL/SQL, 7-9s
Page 208: disabling, 9-4enabling, 9-4error co
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Oracle SQL Developer

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