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- How to use convert function in oracle
- The CONVERT function converts a value in Oracle from one data type to another, and its syntax is CONVERT(<result data type>, <input value>). It can be used to convert string to number, number to string, date to string, string to date, binary to string and string to binary.
- Oracle 532 2024-05-02 23:18:18
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- What does nvl mean in oracle
- The NVL function in Oracle is used to handle null values, it checks if expr1 is null and returns expr2 if it is null, otherwise it returns expr1. Advantages include preventing errors, returning user-friendly values, and simplifying queries. The limitation is that it can only handle a single value and the replacement value must be compatible with expr1's data type.
- Oracle 1197 2024-05-02 23:15:48
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- How to use ifnull in oracle
- The Oracle IFNULL function is used to return a default value when a specified column or expression is NULL. Its uses include: replacing NULL values to prevent errors. Missing data were imputed for data analysis. Convert NULL values to specific values to improve readability.
- Oracle 648 2024-05-02 23:15:31
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- usage of distinct in oracle
- The DISTINCT operator removes duplicate rows from a result set and can be used to extract unique values or eliminate duplicate rows in join results. It can be applied to a single table, use multiple tables to eliminate duplicate rows, or use multiple columns as parameters. DISTINCT may affect query performance because it does not utilize indexes and may increase processing time.
- Oracle 558 2024-05-02 23:12:56
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- Concat usage in oracle
- The CONCAT function in Oracle is used to concatenate multiple strings into one. The usage is CONCAT(string1, string2, ...). The input is multiple strings and the output is the new string after concatenation. It supports NULL value handling and automatic string conversion to insert text using delimiters. However, it is recommended to use the DBMS_LOB.APPEND or STRINGAGG function to optimize performance when connecting to a large number of connections.
- Oracle 1003 2024-05-02 23:12:38
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- The difference between where and having in oracle
- The difference between WHERE and HAVING clauses is scope: WHERE filters the base row, and HAVING filters the grouped result set. WHERE is used for single row conditions and HAVING is used for group result conditions. WHERE comes after FROM and before SELECT, HAVING comes after GROUP BY. WHERE can be used alone, HAVING must be used with a group operation.
- Oracle 994 2024-05-02 23:12:18
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- The difference between sum and count in oracle
- SUM in Oracle is used to calculate the sum of non-null values, while COUNT counts the number of non-null values of all data types, including duplicate values.
- Oracle 532 2024-05-02 23:09:52
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- How to use like in oracle
- The LIKE clause is used to find a string pattern in a table that contains a specific sequence of characters, by specifying the pattern wildcard characters percent sign (%) and underscore (_) to match character sequences and single characters. It also allows the use of square brackets to specify character sets and exclude character sets, as well as the use of escape characters to escape wildcards for literal matching.
- Oracle 839 2024-05-02 23:09:33
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- trunc usage in oracle
- The TRUNC function truncates the specified part of a number or date and retains the required part. The usage is TRUNC(expr, fmt), where: expr is the number or date expression to be truncated, and fmt is the specified part to be truncated. Example: truncate the date to the month and return the first day of the month; truncate the number to an integer and return the number without the decimal part.
- Oracle 700 2024-05-02 23:09:17
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- Usage of rtrim function in oracle
- The RTRIM function in Oracle is used to remove spaces at the end of a string. Usage: Syntax: RTRIM (string) Parameters: string - the string that needs to be processed Return value: the new string after removing trailing spaces Note: only trailing spaces are removed, and other white space characters are not affected; if there are no trailing spaces, the original text is returned; Not valid for NULL values.
- Oracle 744 2024-05-02 23:06:49
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- case usage in oracle
- CASE expressions in Oracle are used to evaluate conditions and return results based on different conditions. The syntax is: CASE WHEN condition THEN result ELSE default result END. Usage includes: 1. Determine conditions; 2. Return results; 3. Specify default results (optional). CASE expressions are readable, scalable, and improve performance, but the conditions must be mutually exclusive and the default result prevents NULL values from being returned.
- Oracle 724 2024-05-02 23:03:51
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- The difference between null and empty in oracle
- NULL means missing or unknown, while NULL means an empty string or zero value. In a query, NULL is not equal to any value, and a null value is equal to a null value of the same type; the field must be explicitly defined to allow NULL, and null values can exist in any field. Understanding the difference between NULL and empty is critical to writing accurate SQL queries and managing data.
- Oracle 747 2024-05-02 23:03:35
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- How to write the output parameters of the call calling process in Oracle
- When you use the CALL statement in Oracle to call a stored procedure or function that contains output parameters, you need to: Declare the name and data type of the output parameters. Pass output parameters as parameters in the CALL statement. Use the PUT_LINE function in the DBMS_OUTPUT package to print the value of the output parameter.
- Oracle 1027 2024-05-02 23:03:18
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- What does call mean in oracle
- The CALL statement in Oracle can be used to call a stored procedure or function. It works by encapsulating reused code, optimizing performance, and encapsulating data access. The steps include: 1. Define stored procedures or functions; 2. Call stored procedures or functions.
- Oracle 399 2024-05-02 23:01:03
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- How to use call in oracle
- The CALL command in Oracle is used to call a stored procedure by specifying the stored procedure name and providing input parameters (if required). Benefits include code reuse, security enhancements, and performance optimizations. Attention needs to be paid to user permissions, parameter order, and declaration of output parameters.
- Oracle 1043 2024-05-02 23:00:48
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