Grid, Services and Clustering with Oracle 10g RAC is the best book in its category, very well structured and explain very well the implementation approach, ASM, Services, and Data Guard/RMAN. Really a must have !!
O’Reilly Media have almost the best books for SQL and PL/SQL for Oracle especially the Oracle PL/SQL Programming, 4th Edition and the SQL Cookbook. Two great references for developers, easy to read with in-depth analysis of the PL/SQL language with practical examples.
Finally two recommandation for Oracle certification : Oracle Database 10g OCP Certification All-In-One Exam Guide and the Sybex OCP: Oracle 10g Certification Kit (1Z0-042 and 1Z0-043). These two books are almost all you need to pass the OCA exam !! The first by Mcgraw-Hill Osborne Media is much more easier to read and understand compared to Sybex. With practice of all what you read in these books you should get the best marks in the OCA exam.
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