Add Model files wiki page.
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go-jet
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6 changed files with 149 additions and 92 deletions
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@ -181,91 +181,3 @@ var MpaaRating = &struct {
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}
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```
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#### Model files
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Sample model file for table `film`:
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```
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package model
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import (
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"time"
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)
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type Film struct {
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FilmID int32 `sql:"primary_key"`
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Title string
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Description *string
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ReleaseYear *int32
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LanguageID int16
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RentalDuration int16
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RentalRate float64
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Length *int16
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ReplacementCost float64
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Rating *MpaaRating
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LastUpdate time.Time
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SpecialFeatures *string
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Fulltext string
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}
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```
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For every column of table `film` there is appropriate field in model type.
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Fields corresponding to primary key columns are tagged with `sql:"primary_key"`.
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This tag is used during query execution to group row results into desired arbitrary structure. See more at TODO:
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Fields are pointer types, if they relate to column that can be NULL.
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Mappings of database types to Go types:
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| Database type(postgres) | Go type |
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| ----------------------------------------------- | -------------------------------------------------- |
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| boolean | bool |
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| smallint | int16 |
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| integer | int32 |
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| bigint | int64 |
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| real | float32 |
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| numeric, decimal, double precision | float64 |
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| date, timestamp, time(with or without timezone) | time.Time |
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| bytea | []byte |
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| uuid | uuid.UUID |
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| enum | enum name |
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| text, character, character varying, | |
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| and all remaining types | string |
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Part of the sample model file for enum `mpaa_rating`:
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```
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package model
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import "errors"
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type MpaaRating string
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const (
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MpaaRating_G MpaaRating = "G"
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MpaaRating_PG MpaaRating = "PG"
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MpaaRating_PG13 MpaaRating = "PG-13"
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MpaaRating_R MpaaRating = "R"
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MpaaRating_NC17 MpaaRating = "NC-17"
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)
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```
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For a reference SQL table definition of table `film`:
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```
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CREATE TABLE dvds.film (
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film_id integer DEFAULT nextval('dvds.film_film_id_seq'::regclass) NOT NULL,
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title character varying(255) NOT NULL,
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description text,
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release_year dvds.year,
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language_id smallint NOT NULL,
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rental_duration smallint DEFAULT 3 NOT NULL,
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rental_rate numeric(4,2) DEFAULT 4.99 NOT NULL,
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length smallint,
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replacement_cost numeric(5,2) DEFAULT 19.99 NOT NULL,
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rating dvds.mpaa_rating DEFAULT 'G'::dvds.mpaa_rating,
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last_update timestamp without time zone DEFAULT now() NOT NULL,
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special_features text[],
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fulltext tsvector NOT NULL
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);
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```
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140
wiki/Model-data.md
Normal file
140
wiki/Model-data.md
Normal file
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@ -0,0 +1,140 @@
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## Model files
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Model files are simple data files used to store result of SQL queries. They are
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autogenerated from to database tables and enums.
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### Table model files
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Following rules are applied to generate model files from database tables:
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- for every table there is one Go file generated. File name is in snake case of the table name.
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- every model file contains one struct type.
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Type name is a camel case of table name.
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- for every column of table there is a field in model struct. Field name is camel case of column name.
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See below table for type mapping.
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- fields are pointer types, if they relate to column that can be NULL.
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- fields corresponds to primary key columns are tagged with `sql:"primary_key"`.
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_This tag is used during query execution to group row results into desired arbitrary structure.
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See more at [Execution](https://github.com/go-jet/jet/wiki/Execution):_
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##### Mappings of database types to Go types
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| Database type(postgres) | Go type |
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| ----------------------------------------------- | -------------------------------------------------- |
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| boolean | bool |
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| smallint | int16 |
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| integer | int32 |
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| bigint | int64 |
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| real | float32 |
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| numeric, decimal, double precision | float64 |
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| date, timestamp, time(with or without timezone) | time.Time |
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| bytea | []byte |
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| uuid | uuid.UUID |
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| enum | enum name |
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| text, character, character varying, | |
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| and all remaining types | string |
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#### Example:
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Sql table `address`:
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```
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CREATE TABLE dvds.address
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(
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address_id serial NOT NULL DEFAULT,
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address character varying(50) NOT NULL,
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address2 character varying(50),
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district character varying(20) NOT NULL,
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city_id smallint NOT NULL,
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postal_code character varying(10),
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phone character varying(20) NOT NULL,
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last_update timestamp without time zone NOT NULL DEFAULT now(),
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CONSTRAINT address_pkey PRIMARY KEY (address_id)
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)
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```
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Autogenerated model file `address.go`:
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```
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package model
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import (
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"time"
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)
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type Address struct {
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AddressID int32 `sql:"primary_key"`
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Address string
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Address2 *string
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District string
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CityID int16
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PostalCode *string
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Phone string
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LastUpdate time.Time
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}
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```
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### Enum model files
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Following rules are applied to generate model files from database enums:
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- for every enum there is one Go file generated. File name is a snake case of enum name.
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- every file contains one renamed string type. Type name is a camel case of enum name.
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Enum type has two helper methods to:
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- initialize correctly from database query result
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- easily convert enum to string.
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- for every enum value there is one constant defined.
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Name of the constant is in format [camel case of enum_name]_[camel case of enum_value_name].
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#### Example
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Enum `mpaa_rating`:
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```
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CREATE TYPE dvds.mpaa_rating AS ENUM
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('G', 'PG', 'PG-13', 'R', 'NC-17');
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```
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Autogenerated model file `mpaa_rating.go`
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```
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package model
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import "errors"
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type MpaaRating string
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const (
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MpaaRating_G MpaaRating = "G"
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MpaaRating_Pg MpaaRating = "PG"
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MpaaRating_Pg13 MpaaRating = "PG-13"
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MpaaRating_R MpaaRating = "R"
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MpaaRating_Nc17 MpaaRating = "NC-17"
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)
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func (e *MpaaRating) Scan(value interface{}) error {
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if v, ok := value.(string); !ok {
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return errors.New("Invalid data for MpaaRating enum")
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} else {
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switch string(v) {
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case "G":
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*e = MpaaRating_G
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case "PG":
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*e = MpaaRating_Pg
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case "PG-13":
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*e = MpaaRating_Pg13
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case "R":
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*e = MpaaRating_R
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case "NC-17":
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*e = MpaaRating_Nc17
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default:
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return errors.New("Inavlid data " + string(v) + "for MpaaRating enum")
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}
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return nil
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}
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}
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func (e MpaaRating) String() string {
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return string(e)
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}
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```
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@ -224,7 +224,7 @@ rRatingFilms := Film.
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WHERE(Film.Rating.EQ(enum.MpaaRating.R)).
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AsTable("rFilms")
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```
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`AsTable("rFilms")` - allows SELECT statements to be seen as table.
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`AsTable("rFilms")` - allows SELECT statements to be seen as source table.
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To use sub-query columns in SELECT statement expressions we have to export column from sub-query,
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using `From` method.
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@ -1,7 +1,7 @@
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* [Installation](https://github.com/go-jet/jet/wiki/Installation)
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* [Generator](https://github.com/go-jet/jet/wiki/Generator)
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* [Model data](https://github.com/go-jet/jet/wiki/Model-data.md)
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* [Model files](https://github.com/go-jet/jet/wiki/Model-data.md)
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* [Writing SQL in Go]()
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* [Expressions](https://github.com/go-jet/jet/wiki/Expressions)
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* [Statements](https://github.com/go-jet/jet/wiki/Statements)
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@ -10,4 +10,4 @@
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* [UPDATE](https://github.com/go-jet/jet/wiki/UPDATE)
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* [DELETE](https://github.com/go-jet/jet/wiki/DELETE)
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* [LOCK](https://github.com/go-jet/jet/wiki/LOCK)
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* [Execution]()
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* [Execution](https://github.com/go-jet/jet/wiki/Execution)
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