SQL JOINs visualized
Copyright © 2009-2015. All rights reserved. This blog is called myNoSQL and it is written by me, Alex Popescu, a software architect with a passion for open source and communities. It records my readings, learnings, and opinions on NoSQL databases, polyglot persistence, and distributed systems -- subjects that I'm passionate about. The opinions expressed here are my own, and no other party necessar
SQLでfloat型を使うということ - iakioの日記
9章 ラウンディングエラー(丸め誤差)より floatを使う場合に精度に注意すべきという点については同意です。 SELECT * FROM Accounts WHERE hourly_rate = 59.95; このため、account_idが123の行hourly_rate列にサイド59.95を割り当てても、リテラル値59.95とは等価になりません。 Accounts.hourly_rateがfloat型のとき、MySQLとは異なりPostgreSQLでは、このクエリは59.95が格納された行を返却する。 これはMySQLでのfloat型が単精度であるのに対して、PostgreSQLのfloat型は倍精度だからだ。単精度浮動小数点型であるreal又はfloat4を使うとMySQLと同様マッチしなくなる。 この時点でもうfloatのことなんて考えたくなくなるところだ。 さてAccounts
4.1. Lexical Structure
SQL input consists of a sequence of commands. A command is composed of a sequence of tokens, terminated by a semicolon (“;”). The end of the input stream also terminates a command. Which tokens are valid depends on the syntax of the particular command. A token can be a key word, an identifier, a quoted identifier, a literal (or constant), or a special character symbol. Tokens are normally separate
Squiggle SQL Builder
The source and downloads can now be found on the squiggle-sql project on Google Code. Squiggle is a little Java library for dynamically generating SQL SELECT statements. It's sweet spot is for applications that need to build up complicated queries with criteria that changes at runtime. Ordinarily it can be quite painful to figure out how to build this string. Squiggle takes much of this pain a
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Casinonic Australia – how to get much pleasure?
