Apache Presto 简明教程

Apache Presto - Basic SQL Operations

在本章中，我们将讨论如何在 Presto 上创建并执行查询。我们来了解一下 Presto 支持的基本数据类型。

In this chapter, we will discuss how to create and execute queries on Presto. Let us go through Presto supported basic data types.

下表描述了 Presto 的基本数据类型。

The following table describes the basic data types of Presto.

S.No	Data type & Description
1.	VARCHAR Variable length character data
2.	BIGINT A 64-bit signed integer
3.	DOUBLE A 64-bit floating point double precision value
4.	DECIMAL A fixed precision decimal number. For example DECIMAL(10,3) - 10 is precision, i.e. total number of digits and 3 is scale value represented as fractional point. Scale is optional and default value is 0
5.	BOOLEAN Boolean values true and false
6.	VARBINARY Variable length binary data
7.	JSON JSON data
8.	DATE Date data type represented as year-month-day
9.	TIME, TIMESTAMP, TIMESTAMP with TIME ZONE TIME - Time of the day (hour-min-sec-millisecond) TIMESTAMP - Date and time of the day TIMESTAMP with TIME ZONE - Date and time of the day with time zone from the value
10.	INTERVAL Stretch or extend date and time data types
11.	ARRAY Array of the given component type. For example, ARRAY[5,7]
12.	MAP Map between the given component types. For example, MAP(ARRAY[‘one’,’two’],ARRAY[5,7])
13.	ROW Row structure made up of named fields

Presto 运算符列在以下表中。

Presto operators are listed in the following table.

S.No	Operator & Description
1.	Arithmetic operatorPresto supports arithmetic operators such as +, -, *, /, %
2.	Relational operator<,>,⇐,>=,=,<>
3.	Logical operatorAND, OR, NOT
4.	Range operatorRange operator is used to test the value in a specific range. Presto supports BETWEEN, IS NULL, IS NOT NULL, GREATEST and LEAST
5.	Decimal operatorBinary arithmetic decimal operator performs binary arithmetic operation for decimal type Unary decimal operator − The - operator performs negation
6.	String operatorThe *‘
	’ operator* performs string concatenation
7.	Date and time operatorPerforms arithmetic addition and subtraction operations on date and time data types
8.	Array operatorSubscript operator[] - access an element of an array Concatenation operator
	- concatenate an array with an array or an element of the same type
9.	Map operatorMap subscript operator [] - retrieve the value corresponding to a given key from a map