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- The difference between varchar2 and char in oracle
- Key differences between VARCHAR2 and CHAR data types in Oracle: VARCHAR2: variable length, stores actual string length; CHAR: fixed length, padded with spaces. VARCHAR2: high storage and retrieval efficiency; CHAR: fast retrieval, low storage and update efficiency. VARCHAR2: comparison is based on actual content; CHAR: comparison is based on padding length. VARCHAR2: stores variable-length strings; CHAR: stores fixed-length strings.
- Oracle 793 2024-05-07 13:15:30
- How to compare dates in oracle
- Oracle provides date comparison capabilities using operators such as = (equal), > (greater than), and < (less than). Use the DATE data type to store date values and support specifying comparison dates through arguments or bind variables. Additionally, AND and OR operators are provided for multiple date comparisons, as well as special rules for handling NULL values. Other date comparison-related functions provided by Oracle include ADD_MONTHS, ADD_DAYS, and BETWEEN.
- Oracle 284 2024-05-07 13:12:16
- What are the functions of the spool command in Oracle?
- The SPOOL command in Oracle redirects query output to a file for persistence, debugging, or integration with other applications. The command syntax is: SPOOL [file_name] [APPEND | REPLACE], where file_name specifies the output file, APPEND appends the output, and REPLACE overwrites the existing file.
- Oracle 733 2024-05-07 13:09:14
- How to use split() function in oracle
- The SPLIT() function splits a string into an array by a specified delimiter, returning a string array where each element is a delimiter-separated portion of the original string. Usage includes: splitting a comma-separated list of values into an array, extracting filenames from paths, and splitting email addresses into usernames and domains.
- Oracle 834 2024-05-07 13:06:16
- Function to intercept string in oracle
- Oracle provides two string interception functions: substr(): intercepts characters of the specified length starting from the specified position. substring(): intercept the remaining characters from the specified position, or intercept the characters of the specified length from the specified position.
- Oracle 1071 2024-05-03 00:24:51
- exception usage in oracle
- EXCEPTION is used to handle exception conditions in SQL or PL/SQL by executing handling code for a specific exception type through the EXCEPTION block. Oracle provides predefined exception types (such as NO_DATA_FOUND, TOO_MANY_ROWS), which can handle different exception types as needed. Best practices recommend always handling exceptions explicitly and providing clear error messages.
- Oracle 340 2024-05-03 00:24:36
- exec usage in oracle
- EXEC is an Oracle statement used to execute stored procedures or other SQL statements. Use EXEC syntax: EXEC [schema_name.]procedure_name [parameter1, parameter2, ...] (where [schema_name] is the stored procedure schema, [procedure_name] is the stored procedure name, [parameter1, parameter2, ...] is the optional parameter ). EXEC can be used to call stored procedures, execute complex SQL statements, encapsulate SQL statements, and improve performance.
- Oracle 989 2024-05-03 00:24:18
- How to convert decode to pg in oracle
- For the Oracle DECODE function in PostgreSQL, you can use a CASE expression or a union. The CASE expression returns the first matching result based on the condition. The syntax is: CASE WHEN condition THEN result ELSE result END. A union combines multiple SELECT statements using the UNION ALL operator, returning a table containing the result columns that satisfy each condition.
- Oracle 706 2024-05-03 00:21:53
- Usage of instr in oracle
- The INSTR function is used in Oracle to find the position of the first match of a substring in a string, returning the position of the match (starting from 1), or 0 if there is no match. Other uses include: finding character positions, case-sensitive searches, and finding multiple matches.
- Oracle 708 2024-05-03 00:21:17
- How to use declare in oracle
- The DECLARE statement in Oracle declares objects such as variables, constants, and cursors. The syntax is: DECLARE [modifier] identifier data type [DEFAULT default value] [, ...], used to store temporary data, multiple reference values, or process cursors.
- Oracle 519 2024-05-03 00:18:51
- How to replace rownum in oracle
- In addition to Oracle's ROWNUM pseudo-column, you can obtain the sequence number of a row using the following alternatives: 1. Subquery (using nested subqueries); 2. Analytical functions (such as ROW_NUMBER()); 3. Sequence (for new inserts rows); 4. Temporary table (store row numbers by creating a temporary table).
- Oracle 598 2024-05-03 00:18:32
- What function is the same as the count function in Oracle?
- The COUNT function in Oracle is equivalent to the COUNT() function in SQL. It is used to count the number of non-null values in a specified column or expression, including: COUNT(*): Counts the number of all non-null values in the table. COUNT(column_name): Count the number of non-null values in the specified column. COUNT(DISTINCT column_name): Counts the number of unique non-null values in the specified column.
- Oracle 808 2024-05-03 00:15:43
- Usage of listagg function in oracle
- The LISTAGG function concatenates a set of rows of data into a string, using the specified concatenation character to separate elements. Usage includes: 1. Join all values in a column; 2. Separate values using join characters; 3. Ignore NULL values; 4. Partition by group; 5. Join values sequentially.
- Oracle 414 2024-05-03 00:15:28
- Are null and empty string equivalent in Oracle?
- In Oracle, NULL and empty string are not equal. NULL represents an unknown value and is not equal to any value; an empty string is a string of length 0 that can be equal to other empty strings. The difference between NULL and the empty string is that NULL cannot be used in arithmetic operations or concatenation operations, while the empty string can.
- Oracle 410 2024-05-03 00:12:52
- Usage of regexplike in oracle
- The Oracle REGEXP_LIKE operator is used to perform regular expression matching, check whether a string matches the specified pattern, and return a Boolean value. It supports various metacharacters such as ., *, +, ?, ^, $, [], {}, allowing complex matching patterns. Additionally, it has optional options like match_parameter (match case/multiple lines) and encoding (character encoding).
- Oracle 456 2024-05-03 00:09:51
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