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Chapters 19 and 20

Chapters 19 and 20. Ch. 19: By What Authority? Users Roles Grant and revoke Synonyms Ch. 20: Changing the Oracle Surroundings Indexes Clusters Sequences Tablespaces. Ch. 19: CREATE USER. CREATE USER Create user username identified by password ;

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Chapters 19 and 20

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  1. Chapters 19 and 20 • Ch. 19: By What Authority? • Users • Roles • Grant and revoke • Synonyms • Ch. 20: Changing the Oracle Surroundings • Indexes • Clusters • Sequences • Tablespaces 1

  2. Ch. 19: CREATE USER • CREATE USER • Create user username identified by password; • Create user username identified externally; • Changing passwords • Alter user username identified by password; • Password Management – determined by DBA created profiles. • Password lifetime • Grace period • Account lock rules • Password reuse rules • Moving to another user, connect sqlplus command • CONNECT • CONNECT username • CONNECT username / password 2

  3. Ch. 19: CREATE ROLE • Roles manage sets of privileges. • CREATE ROLE • Create role rolename; • Standard Oracle Roles • CONNECT – connect to database and perform very limited functions. • RESOURCE – for basic users. • DBA – all system privileges. • Maximum roles allowed is set at startup, max_enabled_roles parameter (30 on phoenix). • Roles can have passwords, but do not by default. 3

  4. Ch. 19: GRANT and REVOKE • Grant for object privileges GRANT {privilege, … | ALL} [ (column,…) ] on object to {user | role} [with grant option] [with hierarchy option]; • Grant for system privileges GRANT {system privilege | role | ALL} to {user | role} [, {user | role}, …] [identified by password] [with admin option]; • Revoke takes privileges from roles or users. REVOKE {system privilege | role | ALL} [, {system privilege | role | ALL} …] from {user | role} [, {user | role}, …]; 4

  5. Ch. 19: Synonyms, Examples, Other • What you can grant to other users • Tables: alter, references, index, on commit refresh, query rewrite, all • PL/SQL Procedures and Functions: execute • Sequences: select, alter • Synonyms provide for another name for an object. • CREATE [PUBLIC] SYNONYM SYNONYM FOR SCHEMA.OBJECT[@LINK]; • Examples: • CREATE ROLE MYTEAM; • GRANT MYTEAM TO JOE, TOM, SUE; • GRANT SELECT ON MYTABLE TO MYTEAM; • GRANT UPDATE (COL1) ON MYTABLE TO MYTEAM; • CREATE PUBLIC SYNONYM TAB1 FOR MYSCHEMA.MYTABLE; • Advanced Options for Security by User • Virtual private database (VPD) adds a where clause to all commands issued by the user to restrict data to only his view of the database. • Oracle Label Security uses security labels on all rows, users only have access to those in their hierarchy. 5

  6. Ch. 20: CREATE INDEX • Indexes: • Contains values of data from a table and their location • Pro: Used to speed data retrieval, also can enforce uniqueness. • Con: Slows updates and deletes. • When to use: if columns are typically used in where clause searches • Primary keys and unique constraints create a unique index automatically. • NULL values are not indexed. • Syntax: • CREATE [BITMAP|UNIQUE] INDEX index ON table(COL1 [, COL2…] )[REVERSE]; • Other Oracle Index Features: • Reverse indexes builds an index on the indexed column in reverse byte order thus increasing the dispersal of values. • Bitmap indexes, new in 8 or 8i ?, associates a bitmap to values and only stores the bitmap in the index. Use with low cardinality values (e.g. T/F) • Function based indexes, new in 8i. Normal indexes are not used if a function is used on the where clause column that you’re searching on. 6

  7. Ch. 20: CREATE CLUSTER • Clusters: • Stores different tables physically together. • The cluster key is the column that the data would normally be joined together with. • Syntax Example: • Create cluster BOOKandAUTHOR(col1 varchar2(1000)); • Create table BOOKSHELF (title varchar2(100) primary key, • … ) • cluster BOOKandAUTHOR(title); 7

  8. Ch. 20: CREATE SEQUENCE • Sequences: • Creates a unique sequentially valued number. • Used during insert and update commands usually. • Typically used to create a primary key. • NextVal and CurrVal get the next/current value of the sequence. • Syntax: • Create sequence myseq increment by 1 start with 1; • Insert into CUSTOMER (id, name) values (myseq.nextval, ‘a’); • Update OTHERTABLE set id = myseq.currval; 8

  9. Ch. 20: Tablespaces and terminology • Tablespace • Tablespaces are a logical organization of space. • Tablespaces owns the database’s datafiles. • Database objects are stored within tablespaces. • Database: a logical collection of shared data stored in tablespaces. • File: A physical datafile belonging to a single tablespace. • Segment: A set of one or more extents that contains all the data for a specific structure within a tablespace. • Extent: A set of contiguous data blocks with in a database that make up a segment. • Block: One or more physical file blocks allocated from an existing datafile. 9

  10. Ch. 20: ERD • Entity-Relationship Diagram showing: • Database • Tablespace • Extents • Segments • Files • Blocks 10

  11. Ch. 20: Tablespace clause syntax • Tablespace Clause: indicates Tablespace and other storage options for tables, indexes, constraints. • Storage Clause: indicates how extents are managed, overrides the default storage parameters of tablespace. • Syntax: CREATE TABLEtablename(column_a type NOT NULL,column_b type,...) STORAGE ( INITIAL 100K NEXT 20K MINEXTENTS 1 MAXEXTENTS 99 PCTINCREASE 50 ) TABLESPACE USER_DATA PCTFREE 5 PCTUSED 30; 11

  12. Ch. 20: Tablespace and Segment Example SQL> select file_name, tablespace_name, bytes, blocks from dba_data_files FILE_NAME TABLESPACE_NAME BYTES BLOCKS ------------------------------------------ --------------- ---------- ---------- /opt/oracle/u1/oradata/OS80/users01.dbf USERS 1048576 512 /opt/oracle/u1/oradata/OS80/tools01.dbf TOOLS 26214400 12800 /opt/oracle/u1/oradata/OS80/temp01.dbf TEMP 6291456 3072 /opt/oracle/u1/oradata/OS80/rbs01.dbf RBS 15728640 7680 /opt/oracle/u1/oradata/OS80/system01.dbf SYSTEM 83886080 40960 /opt/oracle/u1/oradata/OS80/n311_t1.dbf USERDATA_N311 95180800 46475 /opt/oracle/u1/oradata/OS80/csgrad_t1.dbf USERDATA_GRAD 10485760 5120 SQL> l 1 select tablespace_name, segment_name, segment_type, bytes, blocks, extents 2 from dba_segments 3* where owner = 'SCOTT' TABLESPACE_NAME SEGMENT_NA SEGMENT_TYPE BYTES BLOCKS EXTENTS --------------- ---------- ------------------ ---------- ---------- ---------- SYSTEM BONUS TABLE 10240 5 1 SYSTEM SALGRADE TABLE 10240 5 1 SYSTEM WORKER TABLE 10240 5 1 SYSTEM TEMP_USERS TABLE 10240 5 1 SYSTEM LEDGER TABLE 20480 10 2 SYSTEM DEPT TABLE 10240 5 1 SYSTEM EMP TABLE 10240 5 1 SYSTEM PK_DEPT INDEX 10240 5 1 SYSTEM PK_EMP INDEX 10240 5 1 9 rows selected. 12

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