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Varrays versus Nested TablesThe Nested tables are differing from varrays in the following ways:1) Varrays have a maximum size, while nested tables do not.2) Varrays are always dense, while nested tables can be sparse. Therefore, you can delete individual elements from a nested table but not from a varray.3) The Oracle stores varray data in-line (in similar tablespace). But, the Oracle stores nested table data out-of-line in a store table, that is a system-generated database table related with the nested table.4) When stored in the database, the varrays retain their ordering and subscripts, while nested tables do not.Which collection type must you use? That totally depends on your wants and the size of the collection. The varray is stored as an opaque object, while a nested table is stored in a storage table with each element mapped to a row in the table. Therefore, if you want efficient queries, then use the nested tables. If you want to retrieve the whole collections as a whole, then use varrays. Though, when collections get very large, it becomes impractical to retrieve more than subsets. Therefore, varrays are better suited for the small collections
Set Operators The Set operators combine the results of the two queries into one result. The INTERSECT returns all the distinct rows selected by both queries. The MINUS returns
THEO R Y OF PANSPERMIA - Arrhenius (1908) postulated the cosmic panspermia theory that claims that organisms existed throughout the universe, and their spores, etc., could
Project Description: I want a database for large governmental and private data sets on one country that will be easily extended to other countries in the future. Also, the datab
what is the use of declare keyword
Using NOT NULL Besides assigning an initial value, the declarations can impose the NOT NULL constraint, as the example below shows: acct_id INTEGER(4) NOT NULL := 9999; You ca
Query: SELECT * FROM EMPLOYEE1; Select 5 columns and all rows from one table Query: SELECT C_ID, COMPANY, BUILDING, DEPARTMENT, BRANCH FROM CONTRACT;
Database Values You can use the SELECT statement to have the Oracle assign values to a variable. For Each and every item in the select list, there must be a matching, type-compa
Natural Join - SQL In the absence of NATURAL JOIN Example has to be replaced by something rather more longwinded, as shown in Example. Example: Joining IS_CALLED and IS_EN
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The SQL ‘CREATE TABLE' scripts for all the tables you have implemented. Note that your tables must correspond exactly to the ERD you have provided in 1. above, or you will lose ma
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