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diff --git a/doc/src/sgml/html/infoschema-columns.html b/doc/src/sgml/html/infoschema-columns.html new file mode 100644 index 0000000..978df68 --- /dev/null +++ b/doc/src/sgml/html/infoschema-columns.html @@ -0,0 +1,337 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>37.17. columns</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="infoschema-column-udt-usage.html" title="37.16. column_udt_usage" /><link rel="next" href="infoschema-constraint-column-usage.html" title="37.18. constraint_column_usage" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">37.17. <code class="literal">columns</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="infoschema-column-udt-usage.html" title="37.16. column_udt_usage">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="information-schema.html" title="Chapter 37. The Information Schema">Up</a></td><th width="60%" align="center">Chapter 37. The Information Schema</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="infoschema-constraint-column-usage.html" title="37.18. constraint_column_usage">Next</a></td></tr></table><hr /></div><div class="sect1" id="INFOSCHEMA-COLUMNS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">37.17. <code class="literal">columns</code></h2></div></div></div><p> + The view <code class="literal">columns</code> contains information about all + table columns (or view columns) in the database. System columns + (<code class="literal">ctid</code>, etc.) are not included. Only those columns are + shown that the current user has access to (by way of being the + owner or having some privilege). + </p><div class="table" id="id-1.7.6.21.3"><p class="title"><strong>Table 37.15. <code class="structname">columns</code> Columns</strong></p><div class="table-contents"><table class="table" summary="columns Columns" border="1"><colgroup><col /></colgroup><thead><tr><th class="catalog_table_entry"><p class="column_definition"> + Column Type + </p> + <p> + Description + </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">table_catalog</code> <code class="type">sql_identifier</code> + </p> + <p> + Name of the database containing the table (always the current database) + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">table_schema</code> <code class="type">sql_identifier</code> + </p> + <p> + Name of the schema containing the table + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">table_name</code> <code class="type">sql_identifier</code> + </p> + <p> + Name of the table + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">column_name</code> <code class="type">sql_identifier</code> + </p> + <p> + Name of the column + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">ordinal_position</code> <code class="type">cardinal_number</code> + </p> + <p> + Ordinal position of the column within the table (count starts at 1) + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">column_default</code> <code class="type">character_data</code> + </p> + <p> + Default expression of the column + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">is_nullable</code> <code class="type">yes_or_no</code> + </p> + <p> + <code class="literal">YES</code> if the column is possibly nullable, + <code class="literal">NO</code> if it is known not nullable. A not-null + constraint is one way a column can be known not nullable, but + there can be others. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">data_type</code> <code class="type">character_data</code> + </p> + <p> + Data type of the column, if it is a built-in type, or + <code class="literal">ARRAY</code> if it is some array (in that case, see + the view <code class="literal">element_types</code>), else + <code class="literal">USER-DEFINED</code> (in that case, the type is + identified in <code class="literal">udt_name</code> and associated + columns). If the column is based on a domain, this column + refers to the type underlying the domain (and the domain is + identified in <code class="literal">domain_name</code> and associated + columns). + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">character_maximum_length</code> <code class="type">cardinal_number</code> + </p> + <p> + If <code class="literal">data_type</code> identifies a character or bit + string type, the declared maximum length; null for all other + data types or if no maximum length was declared. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">character_octet_length</code> <code class="type">cardinal_number</code> + </p> + <p> + If <code class="literal">data_type</code> identifies a character type, + the maximum possible length in octets (bytes) of a datum; null + for all other data types. The maximum octet length depends on + the declared character maximum length (see above) and the + server encoding. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">numeric_precision</code> <code class="type">cardinal_number</code> + </p> + <p> + If <code class="literal">data_type</code> identifies a numeric type, this + column contains the (declared or implicit) precision of the + type for this column. The precision indicates the number of + significant digits. It can be expressed in decimal (base 10) + or binary (base 2) terms, as specified in the column + <code class="literal">numeric_precision_radix</code>. For all other data + types, this column is null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">numeric_precision_radix</code> <code class="type">cardinal_number</code> + </p> + <p> + If <code class="literal">data_type</code> identifies a numeric type, this + column indicates in which base the values in the columns + <code class="literal">numeric_precision</code> and + <code class="literal">numeric_scale</code> are expressed. The value is + either 2 or 10. For all other data types, this column is null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">numeric_scale</code> <code class="type">cardinal_number</code> + </p> + <p> + If <code class="literal">data_type</code> identifies an exact numeric + type, this column contains the (declared or implicit) scale of + the type for this column. The scale indicates the number of + significant digits to the right of the decimal point. It can + be expressed in decimal (base 10) or binary (base 2) terms, as + specified in the column + <code class="literal">numeric_precision_radix</code>. For all other data + types, this column is null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">datetime_precision</code> <code class="type">cardinal_number</code> + </p> + <p> + If <code class="literal">data_type</code> identifies a date, time, + timestamp, or interval type, this column contains the (declared + or implicit) fractional seconds precision of the type for this + column, that is, the number of decimal digits maintained + following the decimal point in the seconds value. For all + other data types, this column is null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">interval_type</code> <code class="type">character_data</code> + </p> + <p> + If <code class="literal">data_type</code> identifies an interval type, + this column contains the specification which fields the + intervals include for this column, e.g., <code class="literal">YEAR TO + MONTH</code>, <code class="literal">DAY TO SECOND</code>, etc. If no + field restrictions were specified (that is, the interval + accepts all fields), and for all other data types, this field + is null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">interval_precision</code> <code class="type">cardinal_number</code> + </p> + <p> + Applies to a feature not available + in <span class="productname">PostgreSQL</span> + (see <code class="literal">datetime_precision</code> for the fractional + seconds precision of interval type columns) + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">character_set_catalog</code> <code class="type">sql_identifier</code> + </p> + <p> + Applies to a feature not available in <span class="productname">PostgreSQL</span> + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">character_set_schema</code> <code class="type">sql_identifier</code> + </p> + <p> + Applies to a feature not available in <span class="productname">PostgreSQL</span> + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">character_set_name</code> <code class="type">sql_identifier</code> + </p> + <p> + Applies to a feature not available in <span class="productname">PostgreSQL</span> + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">collation_catalog</code> <code class="type">sql_identifier</code> + </p> + <p> + Name of the database containing the collation of the column + (always the current database), null if default or the data type + of the column is not collatable + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">collation_schema</code> <code class="type">sql_identifier</code> + </p> + <p> + Name of the schema containing the collation of the column, null + if default or the data type of the column is not collatable + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">collation_name</code> <code class="type">sql_identifier</code> + </p> + <p> + Name of the collation of the column, null if default or the + data type of the column is not collatable + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">domain_catalog</code> <code class="type">sql_identifier</code> + </p> + <p> + If the column has a domain type, the name of the database that + the domain is defined in (always the current database), else + null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">domain_schema</code> <code class="type">sql_identifier</code> + </p> + <p> + If the column has a domain type, the name of the schema that + the domain is defined in, else null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">domain_name</code> <code class="type">sql_identifier</code> + </p> + <p> + If the column has a domain type, the name of the domain, else null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">udt_catalog</code> <code class="type">sql_identifier</code> + </p> + <p> + Name of the database that the column data type (the underlying + type of the domain, if applicable) is defined in (always the + current database) + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">udt_schema</code> <code class="type">sql_identifier</code> + </p> + <p> + Name of the schema that the column data type (the underlying + type of the domain, if applicable) is defined in + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">udt_name</code> <code class="type">sql_identifier</code> + </p> + <p> + Name of the column data type (the underlying type of the + domain, if applicable) + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">scope_catalog</code> <code class="type">sql_identifier</code> + </p> + <p> + Applies to a feature not available in <span class="productname">PostgreSQL</span> + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">scope_schema</code> <code class="type">sql_identifier</code> + </p> + <p> + Applies to a feature not available in <span class="productname">PostgreSQL</span> + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">scope_name</code> <code class="type">sql_identifier</code> + </p> + <p> + Applies to a feature not available in <span class="productname">PostgreSQL</span> + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">maximum_cardinality</code> <code class="type">cardinal_number</code> + </p> + <p> + Always null, because arrays always have unlimited maximum cardinality in <span class="productname">PostgreSQL</span> + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">dtd_identifier</code> <code class="type">sql_identifier</code> + </p> + <p> + An identifier of the data type descriptor of the column, unique + among the data type descriptors pertaining to the table. This + is mainly useful for joining with other instances of such + identifiers. (The specific format of the identifier is not + defined and not guaranteed to remain the same in future + versions.) + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">is_self_referencing</code> <code class="type">yes_or_no</code> + </p> + <p> + Applies to a feature not available in <span class="productname">PostgreSQL</span> + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">is_identity</code> <code class="type">yes_or_no</code> + </p> + <p> + If the column is an identity column, then <code class="literal">YES</code>, + else <code class="literal">NO</code>. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">identity_generation</code> <code class="type">character_data</code> + </p> + <p> + If the column is an identity column, then <code class="literal">ALWAYS</code> + or <code class="literal">BY DEFAULT</code>, reflecting the definition of the + column. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">identity_start</code> <code class="type">character_data</code> + </p> + <p> + If the column is an identity column, then the start value of the + internal sequence, else null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">identity_increment</code> <code class="type">character_data</code> + </p> + <p> + If the column is an identity column, then the increment of the internal + sequence, else null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">identity_maximum</code> <code class="type">character_data</code> + </p> + <p> + If the column is an identity column, then the maximum value of the + internal sequence, else null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">identity_minimum</code> <code class="type">character_data</code> + </p> + <p> + If the column is an identity column, then the minimum value of the + internal sequence, else null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">identity_cycle</code> <code class="type">yes_or_no</code> + </p> + <p> + If the column is an identity column, then <code class="literal">YES</code> if the + internal sequence cycles or <code class="literal">NO</code> if it does not; + otherwise null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">is_generated</code> <code class="type">character_data</code> + </p> + <p> + If the column is a generated column, then <code class="literal">ALWAYS</code>, + else <code class="literal">NEVER</code>. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">generation_expression</code> <code class="type">character_data</code> + </p> + <p> + If the column is a generated column, then the generation expression, + else null. + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">is_updatable</code> <code class="type">yes_or_no</code> + </p> + <p> + <code class="literal">YES</code> if the column is updatable, + <code class="literal">NO</code> if not (Columns in base tables are always + updatable, columns in views not necessarily) + </p></td></tr></tbody></table></div></div><br class="table-break" /><p> + Since data types can be defined in a variety of ways in SQL, and + <span class="productname">PostgreSQL</span> contains additional ways to + define data types, their representation in the information schema + can be somewhat difficult. The column <code class="literal">data_type</code> + is supposed to identify the underlying built-in type of the column. + In <span class="productname">PostgreSQL</span>, this means that the type + is defined in the system catalog schema + <code class="literal">pg_catalog</code>. This column might be useful if the + application can handle the well-known built-in types specially (for + example, format the numeric types differently or use the data in + the precision columns). The columns <code class="literal">udt_name</code>, + <code class="literal">udt_schema</code>, and <code class="literal">udt_catalog</code> + always identify the underlying data type of the column, even if the + column is based on a domain. (Since + <span class="productname">PostgreSQL</span> treats built-in types like + user-defined types, built-in types appear here as well. This is an + extension of the SQL standard.) These columns should be used if an + application wants to process data differently according to the + type, because in that case it wouldn't matter if the column is + really based on a domain. If the column is based on a domain, the + identity of the domain is stored in the columns + <code class="literal">domain_name</code>, <code class="literal">domain_schema</code>, + and <code class="literal">domain_catalog</code>. If you want to pair up + columns with their associated data types and treat domains as + separate types, you could write <code class="literal">coalesce(domain_name, + udt_name)</code>, etc. + </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="infoschema-column-udt-usage.html" title="37.16. column_udt_usage">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="information-schema.html" title="Chapter 37. The Information Schema">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="infoschema-constraint-column-usage.html" title="37.18. constraint_column_usage">Next</a></td></tr><tr><td width="40%" align="left" valign="top">37.16. <code class="literal">column_udt_usage</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 37.18. <code class="literal">constraint_column_usage</code></td></tr></table></div></body></html>
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