Oracle Learning Path-sql-Join query

One, connection query:

1. Internal connection
The maximum number of connection queries used, only the rows in the table that match the criteria are returned. Such as:

/*** Internal connection ***/select j_c.*,j_sc.* from course j_c INNER join SC j_sc on j_c.cno = J_sc. CNO;

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2. Left Outer connection

Left OUTER join: Returns all rows in the left table, in addition to the rows that match the criteria.

/************************** left outer connection **/select j_c.*,j_sc.* from course j_c Ieft join SC j_sc on j_c.cno = J_sc. CNO;

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3. Right outer connection

Right OUTER join: Returns all rows in the right table, in addition to the rows that match the criteria.

/************************** right outer connection **/select j_c.*,j_sc.* from course j_c R join SC j_sc on j_c.cno = J_sc. CNO;

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4. Full-Outer connection

Full outer joins: Returns rows that do not match the criteria in the left and right tables, in addition to and return rows that meet the criteria

/************************** full outer connection **/select j_c.*,j_sc.* from course j_c Complete join SC j_sc on j_c.cno = J_sc. CNO;

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5. Cross-Connect

Cross connection: That is, the non-write connection condition or invalid connection condition forms the Cartesian product. (The default query)

/************************** Cross connect **/select j_c.*,j_sc.* from course J_c crosses join SC j_sc; Select j_c.*,j_sc.* from Course J_c, SC j_sc;

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Oracle Learning Path-sql-Join query