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- How to use intersect in oracle
- The INTERSECT operator is used to find rows that are common to two or more tables, that is, rows that appear in all tables at the same time. Usage is as follows: Each SELECT statement specifies a list of columns to compare. INTERSECT compares corresponding column values and includes the row if all values are equal. You can use the UNION clause to combine the results with INTERSECT results from other tables.
- Oracle 581 2024-05-09 21:06:19
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- Usage of ceil function in oracle
- The CEIL function in Oracle rounds a number to the nearest integer: Syntax: CEIL(number) Parameters: The number to be rounded Return value: Round to the nearest integer Purpose: Rounding, converting decimals to integers, Example of truncating the decimal part: CEIL(12.34) returns 13, CEIL(-45.67) returns -45
- Oracle 1119 2024-05-09 21:00:23
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- What is the indexing mechanism in oracle
- An index in Oracle is a data structure used to find data quickly. It creates a copy of table column values and avoids a full table scan. Supports B-Tree, Bitmap, Hash, reverse key, XML and other index types, created through the CREATE INDEX command; Oracle automatically maintains the index; using indexes can reduce query time, improve performance, support more complex and faster queries, and simplify data Maintenance; however, it should be noted that indexes occupy storage space, maintaining indexes incurs additional overhead, and not all queries can benefit from indexes.
- Oracle 865 2024-05-09 20:57:17
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- How to use index in oracle
- Indexes in Oracle are used to quickly find data and optimize query performance. They can be used to create indexes, maintain indexes, and use indexes in queries. Benefits of indexes include increasing query speed, reducing I/O operations, optimizing joins, and promoting data integrity. Oracle supports B-Tree, bitmap, function, and hash index types. When selecting an index, you should consider data distribution, query conditions, and table update frequency.
- Oracle 1188 2024-05-09 20:54:18
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- What types of indexes are there in oracle?
- Index types supported by Oracle include: B-Tree index: used for fast equality, range and prefix queries Hash index: used for extremely fast equality query Bitmap index: used to query Boolean fields Function index: used to query functions or The column space index generated by the expression: used to query spatial data. Full-text index: used to search document content. XML index: used to query XML data. LOB index: used to query large object data.
- Oracle 526 2024-05-08 20:15:31
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- Usage of (+ in oracle
- The plus (+) operator in Oracle can be used to: connect strings, numbers, dates, and time intervals; handle NULL values and convert NULL to non-NULL values; convert data types to string types.
- Oracle 723 2024-05-08 20:12:16
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- What does || mean in oracle?
- The || operator in Oracle is used to concatenate two strings and is equivalent to the + operator in other languages. It concatenates two string expressions so that if either operand is NULL, the result will also be NULL. The || operator has higher precedence than the + operator. In addition to concatenating strings, it can be used to concatenate multiple strings, append strings to variables, and create placeholders.
- Oracle 1135 2024-05-08 20:09:20
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- What does (+ mean in oracle
- The "+" symbol in Oracle represents the concatenation operator, which is used to: concatenate strings to form new strings; perform numeric addition operations; concatenate other data types (such as dates or binary data).
- Oracle 934 2024-05-08 20:03:16
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- Drop function in oracle
- The DROP command in Oracle deletes database objects (tables, views, indexes, triggers). This command cannot be reversed and will delete all dependent objects. Usage: DROP <object type> <object name>; object types include TABLE, VIEW, INDEX and TRIGGER. Use the CASCADE keyword to cascade the deletion of dependent objects.
- Oracle 552 2024-05-08 20:00:25
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- interval usage in oracle
- The INTERVAL type in Oracle is used to represent a time period, including time units (such as days, hours) and time quantities (such as 3, 10); it is often used to calculate the difference between date or time values, and its syntax is INTERVAL time_value time_unit, Where time_value is the time quantity, time_unit is the time unit, such as YEAR, MONTH, DAY, etc.; for example, calculate the number of days between two dates: SELECT INTERVAL '2023-06-15' - '2023-05-15' DAY FROM DUAL ;
- Oracle 794 2024-05-08 19:57:18
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- How to use interval in oracle
- The INTERVAL data type in Oracle is used to represent time intervals. The syntax is INTERVAL <precision> <unit>. You can use addition, subtraction, multiplication and division operations to operate INTERVAL, which is suitable for scenarios such as storing time data and calculating date differences.
- Oracle 793 2024-05-08 19:54:19
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- Usage of floor function in oracle
- The FLOOR function in Oracle is used to round a number down to a specified precision (0 means rounding to an integer), the usage is FLOOR(number, precision). It is suitable for calculating averages, sums, rounding amounts, and solving rounding problems involving decimal calculations.
- Oracle 1240 2024-05-08 19:48:16
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- Function to calculate the number of days between two dates in oracle
- The function in Oracle to calculate the number of days between two dates is DATEDIFF(). The specific usage is as follows: Specify the time interval unit: interval (such as day, month, year) Specify two date values: date1 and date2DATEDIFF(interval, date1, date2) Return the difference in days
- Oracle 1452 2024-05-08 19:45:25
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- How to connect strings in oracle
- In Oracle Database, the connection string contains: database host name or IP address, port number, database name, username, and password. Creating a connection string requires concatenating these parts with semicolons. Connecting to the database can use the JDBC API, ODP.NET, or SQL*Plus.
- Oracle 1101 2024-05-08 19:42:18
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- What symbols are used to concatenate strings in oracle
- Strings are concatenated using the double pipe symbol (||) in Oracle, which acts as a concatenation operator to combine string values into a new string. It can connect string values of different data types, including literals, variables, expressions, and column values, for concatenating strings, adding prefixes and suffixes, and formatting output.
- Oracle 570 2024-05-08 19:39:13
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