关键词: 数据挖掘, 决策树, ID3, 嵌入式SQL, 分类

Abstract: As the core algorithm of classification in data mining，ID3 is famous for the merits of easy construction，strong learning ability and high classifying speed.But inherited from machine learning，it has a poor integration with database and can only process data of small scale，which affects its practicality.So an improvement to its core section is proposed based on the inherent ID3 algorithm.Using the embedded SQL，it directly queries the database and then processes received data，then finally acquires a decision table of classification.It is proved that with the improved ID3 combining the high efficiency of SQL and the flexibility of C language，the highly efficient and seamless classification of large data is achieved，which is also greatly improved the processing efficiency.

Key words: data mining, decision tree, ID3, embedded SQL, classification