That lets you pass host arrays to stored functions and procedures. With the Oracle Call Interface (OCI) or the Oracle Precompilers, you can bind host arrays to associative arrays declared as the formal parameters of a subprogram. The most efficient way to pass collections to and from the database server is to set up data values in associative arrays, and then use those associative arrays with bulk constructs (the FORALL statement or BULK COLLECT clause). PL/SQL automatically converts between host arrays and associative arrays that use numeric key values. Passing collections to and from the database server To make an associative array persistent for the life of a database session, declare the associative array (the type and the variable of that type) in a package, and assign values to its elements in the package body.Ī relatively small lookup table, where the collection can be constructed in memory each time a subprogram is invoked or a package is initialized An associative array does not need the disk space or network operations of a database table, but an associative array cannot be manipulated by SQL statements (such as INSERT and DELETE).Īn associative array is intended for temporary data storage. Like a database table, an associative array holds a data set of arbitrary size, and you can access its elements without knowing their positions in the array. Result: Population of Megalopolis is 1000000 ('Population of ' || i || ' is ' || TO_CHAR(city_population(i))) Change value associated with key 'Smallville': TYPE population IS TABLE OF NUMBER - Associative array typeĬity_population population - Associative array variableĬity_population('Megalopolis') := 1000000 Hash tables and other unordered tables in other languages become associative arrays in PL/SQL.Įxample 5-1 Declaring and Populating Associative Array Indexed by String DECLARE Sets and bags in other languages become nested tables in PL/SQL. For example:Īrrays in other languages become varrays in PL/SQL. If you have code or business logic that uses another language, you can usually translate the array and set types of that language directly to PL/SQL collection types. For examples, see "Multidimensional Collections". A nested table type or varray type that is created at schema level (with the "CREATE TYPE Statement") is stored in the database, and you can manipulate it with SQL statements.Ī collection has only one dimension, but you can model a multidimensional collection by creating a collection whose elements are also collections. Actually, there is a limit, but it is very high-for details, see "Collection Element References".ĭense means that the collection has no gaps between elements-every element between the first and last element is defined and has a value (which can be NULL).Ī collection that is created in a PL/SQL block (with the syntax in "Collection") is available only in that block. Unbounded means that, theoretically, there is no limit to the number of elements in the collection. Table 5-1 Characteristics of PL/SQL Collection Types Collection TypeĮither in PL/SQL block or at schema level Restrictions on Record Inserts and Updates Records as Subprogram Parameters and Function Return Values Each record field corresponds to a table column. A record variable can hold a table row, or some columns from a table row. You access each field with this syntax: record_name. In a record, the internal components can be of different data types, and are called fields. Lists and arrays are classic examples of collections. You access each element by its unique subscript. In a collection, the internal components are always of the same data type, and are called elements. In this book, collection or record means both the type and the variables of that type, unless otherwise noted. To create a collection or record variable, you first define a collection or record type, and then you declare a variable of that type. You can pass composite variables to subprograms as parameters. These composite variables have internal components that you can treat as individual variables. If you want to build some query helpers, you can make a struct that implements the clause.This chapter explains how to create and use PL/SQL collection and record variables. Scan scan value into Jsonb, implements sql.Scanner interfaceįunc (j *JSON) Scan(value interfaceĭb.AddError(errors.New( "invalid encryption key")) The customized data type has to implement the Scanner and Valuer interfaces, so GORM knowns to how to receive/save it into the database GORM provides few interfaces that allow users to define well-supported customized data types for GORM, takes json as an example Implements Customized Data Type Scanner / Valuer
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