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- How to use trim in oracle
- The TRIM function in Oracle is used to remove spaces or specific characters at both ends of a string. The syntax is: TRIM([trim_character] FROM string). It can remove all spaces in a string (trim_character parameter is omitted), it can remove specified characters (specify trim_character parameter), or even remove multiple specified characters (specify multiple trim_character parameters). It should be noted that the TRIM function does not remove spaces in the middle of the string.
- Oracle 671 2024-04-30 07:54:15
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- Usage of ltrim function in oracle
- The LTRIM function removes spaces from the left side of a string and returns the original string if there are no spaces. 1. Syntax: LTRIM(string). 2. LTRIM only removes spaces on the left; RTRIM only removes spaces on the right; TRIM removes spaces on both sides. 3. LTRIM returns NULL for NULL values.
- Oracle 595 2024-04-30 07:48:11
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- regr_count usage in oracle
- The REGEXP_COUNT function counts the number of matches of a specific regular expression in a string. It receives two parameters: string and pattern, and returns the number of matches. If there is no match, 0 is returned. Other uses include checking for a match, extracting subgroups of a match, and replacing matches using the REPLACE() function.
- Oracle 1204 2024-04-30 07:42:13
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- How to use count function in oracle
- The COUNT function in Oracle is used to count non-null values in a specified column or expression. The syntax is COUNT(DISTINCT <column_name>) or COUNT(*), which counts the number of unique values and all non-null values respectively.
- Oracle 903 2024-04-30 07:39:13
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- How to use coalesce function in oracle
- The Oracle COALESCE function returns the first non-null value in a set of expressions and is commonly used in data processing and repairing missing values. Usage: 1. Determine the expression to be checked; 2. Specify the COALESCE function; 3. Provide the expression to be checked. This function accepts any number of expressions as parameters and returns the first non-null value, or NULL if all expressions are null.
- Oracle 1105 2024-04-30 07:36:15
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- How to delete table in oracle
- To delete an Oracle table, perform the following steps: 1. Connect to the database; 2. Execute the DROP TABLE command and specify the table name; Note: Deleting a table will permanently delete its data. Please ensure that the table is no longer needed and update the table that depends on it. database object.
- Oracle 464 2024-04-30 07:33:11
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- The difference between blob and clob in oracle
- The main differences between BLOB (Binary Large Object) and CLOB (Character Large Object) in Oracle are: 1. BLOB stores binary data, while CLOB stores character data; 2. The maximum size of BLOB is 4 GB, and the maximum size of CLOB is 4 GB or database block 32 times the size; 3. BLOB does not support indexes, while CLOB supports part of the index; 4. Querying BLOB will load the entire BLOB, while querying CLOB only loads the first 4000 characters; 5. BLOB is stored in the LOB segment, while CLOB
- Oracle 479 2024-04-30 07:30:26
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- Usage of substr in oracle
- The SUBSTR function is used to extract a substring from a string. The syntax is SUBSTR(string, start, length). You need to specify the source string, starting position and length (optional), and the function extracts the substring of the specified length starting from the specified position. For example, SUBSTR('Hello World', 1, 5) returns "Hello" and SUBSTR('Hello World', 7) returns "World".
- Oracle 492 2024-04-30 07:24:16
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- date usage in oracle
- The DATE data type stores date values that do not contain time information. Its uses include saving date information, date operations, and data type conversion. Example usages include: calculating date intervals, comparing dates, and extracting date components. Note that the DATE type does not store time zone information, which ranges from January 1, 4712 BC to December 31, 9999 AD.
- Oracle 1151 2024-04-30 07:21:15
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- The difference between inner join and outer join in oracle
- The connection types in Oracle are divided into inner joins and outer joins. Inner joins return results for matching rows only, while outer joins return matching rows and rows that appear in only one table. There are three types of outer joins: left outer join (returns all rows from the left table), right outer join (returns all rows from the right table), and full outer join (returns all rows from both tables). The characteristic of inner join is to match rows. The left outer join uses NULL to fill the null values of the right table, the right outer join uses NULL to fill the left table null values, and the full outer join uses NULL to fill the null values of both sides of the table.
- Oracle 679 2024-04-30 07:18:17
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- How to use join on in oracle
- The JOIN ON operator in Oracle is used to join tables based on common columns. Its syntax is: SELECT ... FROM table name 1 JOIN table name 2 ON table name 1.common column = table name 2.common column. This operator can be used to join multiple tables and supports other comparison operators and AND operators.
- Oracle 777 2024-04-30 07:15:23
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- How to use union all in oracle
- UNION ALL is used in Oracle to merge result sets from different tables or subqueries while retaining duplicate rows. The specific usage is as follows: merge rows in different tables: SELECT FROM table 1 UNION ALL SELECT FROM table 2 merge duplicate rows in the same table: SELECT FROM table UNION ALL SELECT FROM table
- Oracle 604 2024-04-30 07:09:13
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- How to use union in oracle
- The usage of UNION in Oracle is to merge multiple query result sets with the same structure into a single result set. This operator removes duplicate records unless UNION ALL is used, which merges all records, including duplicates.
- Oracle 844 2024-04-30 07:06:15
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- length usage in oracle
- The LENGTH function returns the number of characters in a string. It accepts CHAR, VARCHAR2, NCHAR, and NVARCHAR2 data types as input, ignores whitespace, and returns an integer result.
- Oracle 1207 2024-04-30 07:00:28
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- casewhen usage in oracle
- The CASE WHEN statement in Oracle is used to return different values based on conditions. Syntax: CASE WHEN condition THEN result ELSE default_result END. Usage: 1. Condition check: WHEN clause contains the condition and returned result; 2. Default result: ELSE clause specifies the default result when any condition is not met. Example: Return income_level based on salary value: salary > 5000: high income; 3000 ≤ salary ≤ 5000: middle income; salary < 3000: low income.
- Oracle 448 2024-04-30 06:57:14
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